How do I choose the right instrument for measuring temperature, pressure, flow, or level in my process?

Selecting the right process instrument starts with defining four things: what variable you need to measure (temperature, pressure, flow, or level), the process conditions the instrument will face (media type, temperature range, pressure range, corrosiveness, and whether the environment is hazardous), the accuracy and response time your application requires, and how the measurement data needs to be communicated (local display only, 4–20 mA signal to a PLC/DCS, or digital protocol like HART or Modbus). For temperature, the choice between thermocouples, RTDs, and infrared sensors depends on the temperature range and accuracy needed. For pressure, gauge type, range, wetted materials, and whether you need local indication or a remote transmitter signal are the key decisions. For flow, the fluid properties (conductive liquid, gas, steam, slurry) determine whether a magnetic, ultrasonic, Coriolis, vortex, or variable-area meter is the best fit. For level, vessel conditions (open vs. pressurized, clean liquid vs. foam/solids) guide the choice between float switches, ultrasonic, radar, or differential pressure technologies. Centro's instrumentation specialists can help you match the right technology to your specific process conditions and budget.

Why is accurate process instrumentation important in industrial operations?

Accurate process instrumentation is the foundation of safe, efficient, and compliant operations. Every control loop — whether it manages boiler pressure, reactor temperature, tank level, or pipeline flow — depends on instruments that provide reliable, real-time measurements. If a temperature sensor reads inaccurately, a heater may overshoot and damage the product or create a safety hazard. If a level transmitter drifts, a tank may overflow or run dry. If a flow meter is undersized, the control system cannot maintain the correct feed rate. Beyond safety and quality, accurate instrumentation directly impacts energy consumption, raw material usage, and regulatory compliance. Calibrated, properly specified instruments reduce waste, prevent unplanned shutdowns, and provide the data required for regulatory reporting and quality documentation.

What is a process control loop and how do instruments fit into it?

A process control loop is a system that continuously measures a process variable, compares it to a desired setpoint, and adjusts an output to keep the variable at the setpoint. The loop consists of three elements: the sensor/transmitter (measures the variable — e.g., a thermocouple measuring temperature), the controller (compares the measurement to the setpoint and calculates a corrective output — typically a PID controller), and the final control element (adjusts the process — e.g., a control valve that opens or closes to change steam flow). Instruments are the eyes and ears of the loop — without accurate, responsive sensors and transmitters, the controller cannot make correct decisions, and the process drifts out of specification. The entire loop must be properly engineered as a system — sensor accuracy, transmitter range, controller tuning, and valve sizing must all be matched to the process requirements.

What are common signal types used in industrial instrumentation?

Industrial instruments communicate with controllers and PLCs using standardized electrical signals. The 4–20 mA analog current loop is the most widely used signal in process instrumentation — it transmits a variable measurement as a proportional current (4 mA = zero/low range, 20 mA = full scale), and the current-based signal is resistant to voltage drop and electrical noise over long cable runs. The 0–10 V DC voltage signal is used in some HVAC and building automation applications but is more susceptible to noise and cable length limitations. Discrete (on/off) signals — from switches, relays, and transmitter alarm contacts — indicate threshold conditions like high level, low pressure, or flow/no-flow. Digital communication protocols — HART (layered on top of 4–20 mA for configuration and diagnostics), Foundation Fieldbus, PROFIBUS PA, and IO-Link — enable bidirectional communication between the instrument and the control system for advanced diagnostics, remote configuration, and multi-variable data.

What should I consider when selecting instruments for a hazardous area?

When instruments are installed in locations classified as hazardous (areas where flammable gases, vapors, or combustible dusts may be present), they must be approved for that classification to prevent ignition. Key considerations include the area classification (Class I for gases/vapors, Class II for dusts, with Division 1 for normally present hazards and Division 2 for abnormal conditions — or Zone 0/1/2 under ATEX/IECEx), the protection method (intrinsic safety, explosion-proof, non-incendive, or purged/pressurized), and the specific gas group and temperature class. Intrinsically safe (IS) instruments — used with IS barriers in the safe area — limit energy to levels too low to cause ignition and are the most common and practical approach for low-power sensors and transmitters. Explosion-proof enclosures contain any internal explosion and are used for higher-power devices. Always verify the instrument's certification (FM, CSA, ATEX, IECEx) matches the area classification before installation.

Instrumentation, Measurement and Control - Dwyer

Instrumentation refers to devices that measure or control physical variables such as temperature, level, flow, or pressure. These products are essential in the industry because they allow for maximum output with mi...

Categories from Dwyer (60)

Thermocouples and RTDs

Thermocouples and RTDs are the most common temperature sensors in industrial processes. They provide accurate readings for control systems, recorders and safety interlocks.

Sensor Types

Thermocouples – types J, K, T, E, N, R and S for wide temperature ranges
RTDs – Pt100 and Pt1000 for high accuracy
Mineral insulated sensors – rugged and bendable
Head-mount assemblies – with transmitters and terminal blocks
Surface and probe sensors – specialized mounting

Choosing a Sensor

Thermocouples handle higher temperatures, while RTDs offer better accuracy and stability. Specify sheath material, length, diameter and connection. Use matching extension wire.

Centro supplies thermocouples and RTDs for temperature measurement.

Temperature Accessories

Temperature accessories help your sensors and instruments read accurately and last longer. Thermowells, fittings, connection heads and extension wire protect sensors from the process and make installation and replacement simpler.

Accessories Available

Thermowells – threaded, socket weld and flanged wells protect sensors from pressure and flow
Compression fittings – adjustable sensor insertion depth
Connection heads – house terminal blocks and head-mount transmitters
Thermocouple and RTD extension wire – carry signals back to the controller
Connectors and plugs – quick disconnects for sensors

Choosing Accessories

Select thermowell material and length for the process, with the tip in the flow, and check the wake frequency calculation for high-velocity lines. Use extension wire that matches the thermocouple type to avoid reading errors. Head and enclosure ratings should match the environment.

Centro carries temperature accessories to complete your sensor installations.

Pressure Transducers

Pressure transducers convert pressure into an electrical signal for PLCs, data loggers and controls. They provide continuous monitoring of hydraulics, pneumatics, water systems, HVAC and process equipment.

Transducer Options

Output types – millivolt, 0-5 V, 0-10 V, 4-20 mA and digital
Gauge, absolute and sealed references – suited to the measurement
Stainless steel wetted parts – compatible with most media
Compact OEM transducers – high-volume machine builds
Hazardous area models – intrinsically safe and explosion-proof

Choosing a Transducer

Select a range so normal pressure sits around 50-75% of full scale, and consider accuracy, temperature effects and overpressure ratings. Protect against pressure spikes with snubbers. Match connectors and cable to the installation.

Centro carries pressure transducers for industrial, mobile and process applications.

Flow Meters

Flow meters measure the rate and total volume of liquids and gases moving through pipes and channels. Accurate flow data supports billing, batching, process control and efficiency improvements.

Flow Meter Types

Magnetic flow meters – conductive liquids with no moving parts
Turbine flow meters – clean, low-viscosity liquids
Positive displacement meters – viscous fluids
Thermal mass meters – gas flow
Rotameters – simple visual indication
Open channel and anemometer meters – water channels and airflow

Choosing a Flow Meter

The fluid, flow range, accuracy, pipe size and installation constraints decide the technology. Consider pressure drop, straight-run needs and output signals.

Centro can help you select flow meters for your fluid and application.

Related categories: Flow Control | Flow Transmitters | Flow Sensors | Flow Switches | Flow Control Accessories

Heat Exchangers

Heat exchangers transfer heat between two fluids without mixing them. They heat process liquids, cool oils and hydraulic systems, recover waste heat and condense steam, and they're used in nearly every process and HVAC industry.

Heat Exchanger Types

Shell and tube – rugged, high pressure and easy to clean
Brazed plate – compact and highly efficient for clean fluids
Gasketed plate and frame – expandable and easy to service
Double-wall and sanitary exchangers – for potable water and food processing
Air-cooled exchangers – reject heat without cooling water

Sizing Information

To size a heat exchanger, you'll need both fluids, their flow rates, inlet and outlet temperatures, allowable pressure drop and operating pressure. Fouling fluids may call for shell and tube or wide-gap plates. Material choices include stainless, copper, titanium and nickel alloys.

Centro can help you size and select a heat exchanger matched to your process conditions.

Visual Flow Meters

Visual flow meters give an at-a-glance reading of flow without power. Sight flow indicators and rotameters confirm flow in cooling, purge, dosing and lubrication lines.

Visual Meter Types

Sight flow indicators – flappers, rotors and drip tubes
Rotameters – variable area flow indication
Paddle wheel indicators – rotating flow display
Glass and plastic bodies – suit pressure and media

Choosing a Meter

Select by flow range, pressure, temperature and fluid compatibility. Visual meters are simple confirmation devices, so add transmitters when you need remote signals.

Centro supplies visual flow meters and sight indicators.

Related categories: Flow Meters | Gas Flow Meters | Thermal Flow Meters | Water Meters | Roto Meters

Pressure Control

Pressure control products measure, monitor and regulate pressure in liquids, gases and steam. Accurate pressure control protects equipment and keeps processes stable.

Pressure Control Products

Gauges – pressure, differential and specialty gauges
Pressure transmitters and transducers – electronic monitoring
Pressure switches – alarm and control set points
Pressure regulators and sequence valves – control downstream pressure
Accessories – snubbers, syphons, manifolds and gauge valves

Building a Measurement Point

Choose instrument range, accuracy and wetted materials, then add the right accessories, such as isolation valves and snubbers, for safe, accurate readings.

Centro supplies pressure control instruments and accessories from leading brands.

PID

PID controllers keep temperature, pressure, flow and level steady by continuously comparing the measured value with set point and adjusting the output. Proportional, integral and derivative actions work together for fast, stable control.

PID Controller Features

Universal inputs – thermocouple, RTD, mA and voltage
Relay, SSR and analog outputs – drive heaters, valves and drives
Auto-tuning – fast setup
Ramp and soak programs – multi-step profiles
Communication – Modbus and Ethernet

Choosing a Controller

Select panel size, inputs, outputs and alarms based on your process. Heat/cool control and multi-loop options handle complex systems.

Centro supplies PID controllers for temperature and process control.

Related categories: Controllers | Process Meters | Panel Meters and Displays

Pressure Transmitters

Pressure transmitters send accurate pressure readings to your control system over long distances. They're the standard instrument for process monitoring, control loops and safety systems.

Transmitter Types

Gauge and absolute transmitters – line pressure measurement
Differential pressure transmitters – flow, level and filter monitoring
Smart transmitters – HART and digital communication
Remote seal transmitters – hot, viscous or corrosive media
Hazardous area models – explosion-proof and intrinsically safe

Choosing a Transmitter

Select range, accuracy, process connection and wetted materials. Consider output, display and approvals. Manifolds simplify installation and calibration.

Centro supplies pressure transmitters and manifolds for process measurement.

Related categories: Pressure Control | Pressure Regulators | Pressure Switch | Sequence Valves | Gauges

Pressure Switch

Pressure switches open or close an electrical contact when pressure reaches a set point. They start and stop pumps and compressors, trigger alarms and shut equipment down when pressure is unsafe.

Pressure Switch Types

Mechanical switches – simple, reliable and no power needed
Electronic switches – adjustable set points and displays
Differential pressure switches – filter and flow monitoring
Vacuum switches – vacuum system control
Explosion-proof switches – hazardous areas

Choosing a Switch

Select set point range, deadband, electrical rating and wetted materials. Fixed or adjustable deadband affects cycling. Add snubbers for pulsating systems.

Centro carries pressure switches for pumps, compressors and process safety.

Gauges

We offer pressure gauges, vital instruments that measure and indicate fluid or gas pressure within a system. These gauges are commonly employed in various industries, including manufacturing, oil and gas, automotive, and HVAC systems. Pressure gauges consist of a dial or digital display that shows the pressure reading and a sensing element that detects the pressure and converts it into a readable form. They come in different types, such as Bourdon tube gauges, diaphragm gauges, and digital pressure gauges, each suited for specific applications and pressure ranges. Pressure gauges provide crucial information for monitoring and controlling processes, ensuring optimal performance and safety. They enable operators to gauge system pressure levels, detect abnormalities, and make informed decisions regarding system adjustments or maintenance. Pressure gauges may also incorporate features such as maximum pressure indicators, adjustable pointers, or alarms for added functionality. With their accuracy, reliability, and ease of use, pressure gauges are crucial in maintaining operational efficiency and safety in various industries.

Panel Meters and Displays

Panel meters and displays turn signals from transmitters, sensors and electrical circuits into clear readings on a control panel. Operators can see flow, temperature, pressure, level, speed or current at a glance, and many models also provide alarms and retransmitted outputs.

Display Options

Process meters – read 4-20 mA and 0-10 V signals in engineering units
Electrical meters – AC/DC voltage, current and power
Temperature displays – direct thermocouple and RTD inputs
Rate and totalizer meters – flow rate, totals and counts from pulse inputs
Large-digit displays – visible across the plant floor

Choosing a Meter

Match the input type and range, then decide whether you need relay alarms, analog retransmission or serial communication. Check the panel cutout size (1/8 DIN is common), power supply and front-panel rating for washdown areas. Loop-powered meters are useful where no separate power is available.

Centro carries panel meters and displays from leading instrumentation brands and can help you match one to your signal.

Related categories: Controllers | Process Meters | PID

Controllers

Process controllers read signals from sensors and adjust outputs to hold temperature, pressure, flow or level at set point. They range from simple panel meters to advanced PID controllers.

Controller Products

PID controllers – precise closed-loop control
Process meters – display and alarm process signals
Panel meters and displays – local indication

Choosing a Controller

Match inputs (thermocouple, RTD, mA, voltage) and outputs (relay, SSR, analog) to your process. Consider alarms, ramp/soak programming and communications. Panel size (1/16, 1/8, 1/4 DIN) affects layout.

Centro offers controllers and displays for process and temperature control.

Shop by type: Panel Meters and Displays | Process Meters | PID

Temperature Measurement, Instrumentation and Control

We carry a complete selection of temperature measurement, instrumentation, and control devices to suit any industrial or commercial application. For various reasons, temperature measurement, instrumentation, and Control products are critical to industrial systems. Thermocouples, for example, are used extensively in industry to measure temperatures in a wide range of applications. Temperature switches are used to control the temperature of a process or system. All three of these products are essential to properly functioning industrial systems. Whether you need a simple temperature gauge for an easy fix or a sophisticated control system for a large factory, we have the products and expertise to meet your needs. Thermocouples, temperature switches, thermometers, and transmitters are available online, and our knowledgeable staff is always on hand to answer any questions. So please browse our selection today and find the perfect solution for your temperature monitoring needs.

Pressure Control Accessories

Pressure control accessories protect instruments, simplify maintenance and make pressure measurements more accurate. Syphons, snubbers, manifolds and valves are essential to a dependable gauge or transmitter installation.

Accessories Available

Pressure snubbers – dampen pulsation and spikes
Syphons – protect gauges from live steam
Manifold valves – isolate and equalize transmitters
Gauge cock and instrument valves – isolate instruments for service
PT plugs – quick test ports for pressure and temperature checks

Building an Installation

A typical gauge installation includes an isolation valve, a protection device (snubber or syphon) and the gauge itself. Choose materials compatible with the media and pressure ratings above system maximum.

Centro carries pressure control accessories to complete and protect your instrument installations.

Related categories: Pressure Control | Gauges | Pressure Transducers | Pressure Switch | Pressure Transmitters

Differential Pressure Gauges

Differential pressure gauges measure the difference between two pressure points. They show filter loading, flow through orifices, level in pressurized tanks and pressure drop across equipment.

DP Gauge Options

Diaphragm DP gauges – low differential ranges
Piston DP gauges – high line pressures
DP gauges with switches – alarms and control
Backflow test kits – backflow preventer testing
Accessories – manifolds and mounting kits

Choosing a DP Gauge

Specify differential range, maximum line pressure, wetted materials and connection. Use 3-valve manifolds to protect gauges during startup.

Centro supplies differential pressure gauges and accessories.

Shop by type: Backflow Test Kits | Differential Pressure Gauge Accessories

Related categories: Pressure Gauges | Digital Gauges | Test Gauges | Commercial Gauges | Process Gauges

Data Loggers

Data loggers record temperature, humidity, pressure, voltage and other readings over time, giving you a dependable record for quality checks, compliance and troubleshooting. Most are small, battery-powered units that can run on their own for weeks or months.

Data Logger Types

Temperature and humidity loggers – cold chain, warehouses and cleanrooms
Process signal loggers – record 4-20 mA and voltage inputs from transmitters
Pressure loggers – monitor water systems and compressed air
Wireless and cloud-connected loggers – view live data and receive alerts remotely
Multi-channel loggers – log several sensors on one device

What to Consider

Define what you need to measure, the sample rate, how long the logger must run and how you'll retrieve the data. For regulated industries, look for calibration certificates and software with audit trails. Wireless loggers save time when many sites or rooms need monitoring.

Centro offers data loggers and software for food, pharmaceutical, HVAC and industrial monitoring.

Related categories: Recorders | Paperless Recorders | Chart Recorders

Thermowells

Thermowells protect temperature sensors from pressure, flow, corrosion and abrasion. They also let you remove sensors for replacement or calibration without draining or shutting down the process.

Thermowell Types

Threaded thermowells – common for general service
Socket weld and weld-in – high-pressure installations
Flanged thermowells – easy removal and corrosive service
Sanitary thermowells – tri-clamp for food and pharma
Tapered and stepped stems – strength and fast response

Choosing a Thermowell

Select material, insertion length, bore size and connection. For high-velocity flows, perform a wake frequency calculation to avoid stem failure.

Centro supplies thermowells for temperature sensors and thermometers.

Bi-Metal Thermometers

Bimetal thermometers are widely used temperature measurement devices that employ a bimetallic strip to indicate temperature changes. These thermometers consist of two metal strips, typically made of different metals with different coefficients of thermal expansion, bonded together. The metals expand or contract at different rates as the temperature changes, causing the bimetallic strip to bend. This bending motion is then translated into a rotational movement displayed on a calibrated dial to indicate the temperature. Bimetal thermometers are known for their simplicity, durability, and cost-effectiveness. They are commonly used in various industries and applications requiring reliable temperature monitoring, such as HVAC systems, automotive, food processing, and industrial processes. Bimetal thermometers offer advantages such as wide temperature ranges, resistance to shock and vibration, and ease of installation. They are available in different sizes and configurations to suit specific application requirements. With their robust construction and accurate temperature indication, bimetal thermometers provide a reliable and cost-effective temperature measurement solution in various industrial and commercial settings.

Related categories: Thermometers | Industrial Thermometers

Temperature Transmitters

Temperature transmitters convert thermocouple and RTD signals into a stable 4-20 mA or digital output. That makes temperature readings more accurate and less prone to noise over long cable runs.

Transmitter Types

Head-mount transmitters – install in sensor connection heads
DIN rail transmitters – panel mounting
Field-mount transmitters – with displays and enclosures
HART and smart transmitters – diagnostics and remote configuration
Isolated transmitters – prevent ground loops

Choosing a Transmitter

Match the input type (thermocouple or RTD), range and output. Consider accuracy, isolation and hazardous area approvals. Integrated sensor-transmitter assemblies simplify ordering.

Centro supplies temperature transmitters and assemblies for process measurement.

Manometers

Manometers measure pressure and differential pressure by balancing it against a column of liquid, or with a digital sensor. They're the go-to tool for low-pressure measurement in HVAC, cleanrooms, combustion setup, gas lines and filter monitoring.

Manometer Types

U-tube manometers – simple, accurate and no power required
Inclined manometers – higher resolution for very low pressures
Digital manometers – handheld instruments with data logging
Differential pressure manometers – filter and duct monitoring

Choosing a Manometer

Select the range and units (inches of water column, Pa or mbar) for your application. Handheld digital models are convenient for technicians, while fixed liquid manometers provide continuous visual indication. Use the correct gauge fluid and keep the instrument level for accurate readings.

Centro offers manometers for HVAC, combustion and low-pressure process measurement.

Related categories: Gauges | Pressure Gauges | Tubular Gauges | Gauge Parts & Accessories | Boiler Gauges

Industrial Gauges

Industrial pressure gauges are built for the vibration, pulsation and rough handling found in plants, pump rooms and machinery. They give operators a dependable local reading of pressure in water, air, oil, steam and process lines.

Industrial Gauge Options

Stainless steel cases – corrosion resistance and durability
Liquid-filled gauges – dampen vibration and pulsation for steady readings
Brass and stainless internals – match media compatibility
Bottom and back connections – for line and panel mounting
Dial sizes from 2" to 6" – readable at a distance

Selecting a Gauge

Choose a range so normal operating pressure sits in the middle of the dial, generally about twice the operating pressure. Use a liquid-filled gauge on pumps and compressors, and add a snubber for pressure spikes. Confirm the connection size and accuracy grade.

Centro carries industrial pressure gauges for plant, process and equipment applications.

Flow Control

Flow control products measure, monitor and regulate the movement of liquids and gases through a process. Accurate flow data helps you control dosing, track usage, protect pumps from running dry and confirm that cooling, lubrication and treatment systems are working.

Flow Control Products

Flow meters – magnetic, turbine, positive displacement, thermal and variable area
Flow switches – alarm or shut down when flow drops too low or rises too high
Flow sensors and transmitters – send continuous flow signals to your control system
pH and conductivity instruments – monitor water quality along with flow
Flow control accessories – fittings, displays and mounting hardware

Choosing a Technology

The fluid decides the technology. Magnetic meters need a conductive liquid, thermal meters are built for gases, and positive displacement meters handle viscous oils. Consider accuracy, pipe size, pressure drop, straight-run requirements and the output your controller needs.

Centro's instrumentation team can help you select flow control products that match your fluid, line size and accuracy needs.

Level Control

Level control is essential for many industrial and commercial applications, ranging from simple water tanks to complex chemical processing systems. Industrial applications often require control to maintain safe and efficient operations. This can be accomplished through the use of float switches or differential pressure control. Float switches are devices used to measure the level of a liquid in a tank. They work by using a float that is attached to a switch. When the float rises or falls with the level of the liquid, the switch is activated. This can then be used to trigger an alarm or shut off a pump. Differential pressure control is another level control method that uses pressure sensors to measure the difference in pressure between two points. This can be used to determine the liquid level in a tank. Differential pressure control is often used in applications requiring precise level control. We carry a complete selection of level-control products to meet your needs. Our float switches are ideal for small-scale applications, while our radar and differential pressure control systems are designed for more demanding environments. We also offer load cells for use in weight-based level measurement. Whether you need a simple float switch or a sophisticated differential pressure system, we have your level control products.

Shop by type: Bulk Solids | Liquid Level

Flow Switches

Flow switches monitor liquid or air flow and trigger alarms or shutdowns when flow is too low or too high. They protect pumps, heat exchangers, chillers and cooling systems.

Flow Switch Types

Paddle flow switches – simple, rugged
Thermal flow switches – no moving parts
Piston and magnetic flow switches – precise set points
Air flow switches – ducts and HVAC

Choosing a Switch

Select by media, flow range, pipe size, pressure and temperature. Adjustable set points add flexibility.

Centro supplies flow switches.

Related categories: Flow Control | Flow Transmitters | Flow Meters | Flow Sensors | Flow Control Accessories

Temperature Switches

Temperature switches open or close a contact at a set temperature to start fans, stop heaters, trigger alarms or shut down equipment. They're simple, dependable temperature protection.

Switch Types

Mechanical switches – bulb and capillary or bimetal
Electronic switches – adjustable set points and displays
Limit switches – high-limit safety shutoff
Explosion-proof switches – hazardous areas

Choosing a Switch

Select range, deadband, contact rating and sensor style. Use thermowells for pressurized systems. Manual-reset limits add safety.

Centro supplies temperature switches for equipment protection and control.

Float Switch

A float switch is a simple, dependable way to monitor liquid level and automate pumps and alarms. As the liquid rises or falls, the float moves and opens or closes a circuit at the set point, with no complex setup or programming.

Common Uses

Pump control – start and stop sump, lift station and transfer pumps
High and low alarms – prevent overflows and dry running
Tank filling – control solenoid valves and fill pumps
Leak detection – sense water in pans and basements

Choosing a Float Switch

Select the mounting style that fits your tank (top, side or cable-suspended) and a float material compatible with the liquid, such as polypropylene, stainless or PVDF. Check the switch rating against your load and use a relay for larger pumps. Specific gravity affects how well the float works.

Centro offers float switches in many materials and styles for water, wastewater and chemical tanks.

Related categories: Liquid Level | Radar | Level Transmitters | Differential Pressure Control | Float Switches

Sight Flow Indicators

Sight flow indicators are essential instruments used to visually monitor the flow of liquids and gases in a pipeline or process system. These transparent or glass-tube indicators allow operators to observe the presence, color, clarity, and flow rate of fluids, ensuring smooth operations and providing valuable insights into the process. Sight flow indicators are commonly used in industries like chemical processing, petrochemicals, pharmaceuticals, and water treatment, where real-time flow observation is critical for safety, quality control, and troubleshooting. With a wide range of designs and materials available, sight flow indicators offer reliable and easy-to-use solutions for monitoring fluid flow and ensuring the efficiency of industrial processes.

Related categories: Flow Meters | Accessories and Parts | Ultrasonic Flow Meters | Water Meters | Gas Flow Meters

Level Transmitters

Level transmitters give a continuous reading of how full a tank, vessel or silo is, usually as a 4-20 mA or digital signal sent to your PLC, display or SCADA system. That live reading supports inventory tracking, pump control, overfill prevention and batching.

Level Transmitter Technologies

Radar – non-contact, unaffected by vapor, temperature or pressure
Ultrasonic – economical non-contact measurement for water and wastewater
Hydrostatic (submersible and flange-mount) – measure level from liquid head pressure
Guided wave radar – reliable in foam, turbulence and interface applications
Magnetostrictive and float – high-accuracy level for custody and inventory

Choosing a Transmitter

Look at the media, tank height, temperature, pressure and any foam, vapor, agitation or buildup. Non-contact radar and ultrasonic avoid wetted parts, while hydrostatic sensors are simple and cost-effective in open tanks. Check the process connection, output and hazardous area approvals.

Centro's instrumentation team can help you pick a level transmitter that handles your tank conditions reliably.

Related categories: Liquid Level | Float Switch | Float Switches | Radar | Differential Pressure Control

Instrumentation Valves

Instrumentation valves provide precise fluid control for measurement, sampling, and process control systems. Shop instrumentation solenoid valves for automated on/off switching in control loops, needle valves for fine flow adjustment in analyzer and transmitter installations, proportioning valves for electronically modulated flow control, and air-actuated valves for remote operation in process environments. Built-in materials like 316 stainless steel, brass, and PTFE, these small-bore instrumentation valves are designed for tight spaces, high pressures, and compatibility with gases, liquids, steam, and corrosive media. Browse our full selection of instrumentation valves below to find the right fit for your application, or contact us for sizing and selection assistance.

Shop by type: Instrumentation Needle Valves | Instrumentation Check Valves

Thermometers

Thermometers give simple, reliable local temperature readings in pipes, tanks, boilers and HVAC systems. They work without power, so they're a dependable backup to electronic sensors.

Thermometer Types

Bi-metal thermometers – rugged dial thermometers
Industrial thermometers – glass and digital models
Adjustable angle thermometers – easy viewing
Thermowells – protect stems and allow removal

Choosing a Thermometer

Select range, stem length, dial size and connection. Use thermowells in pressurized systems. Choose stainless construction for harsh environments.

Centro supplies thermometers and thermowells for industrial and HVAC use.

Shop by type: Bi-Metal Thermometers | Industrial Thermometers

Temperature Sensors

Temperature sensors measure heat in processes, equipment and buildings. They're the most common measurement in industry and are critical for quality, safety and efficiency.

Temperature Sensor Types

Thermocouples – wide ranges and fast response
RTDs – high accuracy and stability
Thermistors – sensitive, low-cost sensing
Infrared sensors – non-contact measurement
Surface and immersion probes – suit installation

Choosing a Sensor

Select by range, accuracy, response time and installation. Use thermowells in pressurized lines, and match extension wire for thermocouples.

Centro supplies temperature sensors and assemblies.

Flow Sensors

Flow sensors detect and measure the movement of liquids and gases in a pipe or duct. They protect pumps from running dry, confirm cooling flow to machines and give your control system the feedback it needs.

Flow Sensor Technologies

Thermal flow sensors – no moving parts, suitable for water, oil and air
Paddle and vane sensors – simple, rugged flow detection
Magnetic inductive sensors – for conductive liquids
Ultrasonic clamp-on sensors – non-invasive measurement on existing pipe
Vortex sensors – steam, gas and liquid applications

Choosing a Sensor

Consider the media, flow range, pipe size, temperature and pressure, and whether you need a switching point, a continuous analog signal or both. IO-Link sensors provide extra diagnostics. Follow the straight-run requirements for accurate readings.

Centro offers flow sensors for machine cooling, process monitoring and pump protection.

Water Meters

Water meters measure water use for billing, sub-metering, process control and conservation. Accurate metering helps you find leaks and control costs.

Water Meter Types

Positive displacement meters – accurate at low flows
Multi-jet meters – commercial service
Turbine meters – higher flows
Electromagnetic meters – no moving parts
Pulse output meters – remote monitoring

Choosing a Meter

Select by flow range, pipe size, accuracy and output. Lead-free meters are required for potable water.

Centro supplies water meters for commercial and industrial use.

Digital Gauges

Digital pressure gauges give precise readings on a clear digital display. Many add data logging, min/max recording and selectable units.

Features

High accuracy – 0.25% or better
Easy-to-read displays – backlit LCDs
Selectable units – psi, bar, kPa and more
Battery and loop-powered – flexible installation
Data logging – record pressure trends

Choosing a Gauge

Select range, accuracy, connection and power source. Digital gauges are ideal for test, calibration and precise monitoring.

Centro supplies digital pressure gauges.

Temperature Controllers

Temperature controllers are devices used to maintain and regulate precise temperatures in different processes and environments. Temperature controllers monitor the temperature of a system and compare it to a set point, making necessary adjustments by activating heating or cooling mechanisms to achieve the desired temperature. They are widely used in applications such as manufacturing, HVAC systems, food processing, and laboratory environments. Temperature Controllers help improve product quality, enhance energy efficiency, and reduce operational costs. Modern temperature controllers often come with advanced features like digital displays, programmable settings, and remote monitoring capabilities, making them versatile and user-friendly tools for maintaining optimal temperature conditions.Not sure which input, output or panel size you need? Our team can match a temperature controller to your sensor, heater and control requirements.

pH probes and transmitters constitute a dynamic duo in the realm of pH measurement, offering sophisticated and precise tools for assessing the acidity or alkalinity of solutions. pH probes, often composed of a sensitive glass electrode and a reference electrode, function by converting the concentration of hydrogen ions into electrical signals. These probes are adept at delivering accurate and real-time pH readings, making them indispensable in laboratory research, industrial processes, and environmental monitoring. Paired with pH transmitters, which amplify and convert the electrical signals from the probes into a format suitable for interpretation and display, these tools provide a comprehensive solution for continuous pH monitoring. pH transmitters offer additional features such as data logging, remote access, and integration with control systems, enhancing their utility in complex industrial operations. This combination of pH probes and transmitters ensures not only precise measurements but also facilitates efficient and automated pH control in diverse applications, contributing to the optimization of processes and the maintenance of desired conditions. Regular calibration and maintenance routines are vital to guarantee the reliability and longevity of these pH tools in critical analytical and industrial settings.

Shop by type: PH Probes | PH Transmitters

Related categories: Analytical Tools | Conductivity

Flow Transmitters

Flow transmitters convert flow measurements into standard signals for control systems, so you can monitor, control and record flow remotely.

Transmitter Options

4-20 mA and HART outputs – standard integration
Pulse outputs – totalizing and batching
Digital communication – Modbus and Ethernet
Remote and integral mounting – suit installation

Choosing a Transmitter

Match the transmitter to the sensor or meter type and output required. Consider display, power and hazardous area ratings.

Centro supplies flow transmitters for process monitoring.

Related categories: Flow Control | Flow Switches | Flow Meters | Flow Sensors | Flow Control Accessories

Accessories and Parts

Flow meter accessories and parts keep flow meters accurate and in service. Replacement sensors, fittings, displays and kits extend meter life.

Parts Available

Replacement sensors and rotors – restore accuracy
Fittings and adapters – installation
Remote displays – read meters from a distance
Cables and connectors – signal wiring
Calibration services – verify accuracy

Ordering Parts

Have your meter model and serial number ready. Some parts require factory calibration.

Centro supplies flow meter accessories and parts.

Related categories: Flow Meters | Sight Flow Indicators | Ultrasonic Flow Meters | Water Meters | Gas Flow Meters

Gas Detection Sensors

Gas detection sensors warn people when toxic or combustible gases reach dangerous levels. They protect workers in plants, confined spaces, treatment facilities and storage areas.

Gas Detection Types

Combustible gas detectors – methane, propane and hydrogen
Toxic gas detectors – H2S, CO, ammonia and chlorine
Oxygen monitors – oxygen deficiency and enrichment
Fixed and portable detectors – area and personal monitoring
Controllers and alarms – alarms and ventilation control

Planning a System

Identify the gases present, their density and where they could collect. Sensor placement matters: lighter gases rise and heavier gases settle. Regular bump testing and calibration are essential.

Centro supplies gas detection sensors and controllers for workplace safety.

Recorders

Recorders document process conditions over time for quality control, regulatory compliance and troubleshooting. Options range from traditional chart recorders to modern paperless and data logging systems.

Recorder Types

Paperless recorders – digital recording with trend displays
Chart recorders – circular and strip charts
Data loggers – compact, battery-powered recording

Choosing a Recorder

Consider the number of inputs, recording interval, data retrieval and compliance needs. Paperless recorders eliminate charts and pens and simplify data export.

Centro supplies recorders, charts, pens and data loggers.

Shop by type: Data Loggers | Paperless Recorders | Chart Recorders

Conductivity

Conductivity analytical tools play a pivotal role in measuring the ability of a solution to conduct electric current, providing valuable insights into the concentration of dissolved ions. These tools are widely used in various scientific, industrial, and environmental applications to assess the purity and composition of liquids. The principle underlying conductivity measurements involves the detection of ions, which enhance electrical conductivity in a solution. The greater the concentration of ions, the higher the conductivity. Commonly employed in water quality testing, pharmaceutical manufacturing, and chemical process control, conductivity analytical tools assist in monitoring the effectiveness of water treatment processes, ensuring compliance with regulatory standards, and maintaining the integrity of industrial processes. The versatility of conductivity measurements extends to applications such as detecting contaminants, assessing the salinity of water bodies, and optimizing the efficiency of chemical reactions. Regular calibration and maintenance are essential to ensure the accuracy and reliability of conductivity analytical tools, contributing to their indispensable role in analytical chemistry and industrial quality control.

Shop by type: Conductivity Probes | Conductivity Transmitters

Related categories: Analytical Tools | pH

Paperless Recorders

Paperless recorders capture process data such as temperature, pressure, flow and level digitally, so there are no paper charts or pens to buy. They show live trends on a color screen and store months of data for quality records, troubleshooting and compliance.

Key Features

Multiple universal inputs – thermocouple, RTD, mA and voltage
Color trend displays – real-time and historical views
Secure data storage – SD card, USB and network export
Alarms and math functions – totalizing, averaging and relay outputs
Audit trail options – FDA 21 CFR Part 11 compliance

Choosing a Recorder

Count the inputs you need now and plan for future growth. Check communication options (Ethernet, Modbus, web server), panel cutout size and software for reviewing data. Replacing chart recorders often pays for itself in saved consumables and staff time.

Centro offers paperless recorders and can help you migrate from paper chart recorders.

Related categories: Recorders | Chart Recorders | Data Loggers

Industrial Thermometers

Industrial thermometers are specialized devices used to measure temperature in various industrial applications. These thermometers are designed to withstand harsh environmental conditions and provide accurate temperature readings in industrial settings. They are constructed with durable materials, such as stainless steel or ruggedized plastic, to withstand high temperatures, pressure, and vibrations. Industrial thermometers come in various types, including bimetallic thermometers, gas-actuated thermometers, infrared thermometers, and digital thermometers. They are used in industries such as manufacturing, oil and gas, HVAC, and food processing, where precise temperature control is critical for operational efficiency and safety. Industrial thermometers offer features such as wide temperature ranges, high accuracy, and corrosion resistance. They are often equipped with protective features like IP ratings or explosion-proof enclosures to ensure safe and reliable operation in hazardous environments. With their ability to provide reliable temperature measurements, industrial thermometers are crucial in process control, quality assurance, and monitoring critical temperature parameters in various industrial applications.

Related categories: Thermometers | Bi-Metal Thermometers

Turbine Flow Meters

Turbine flow meters measure liquid flow by counting the rotation of a turbine rotor. They're accurate and responsive in clean, low-viscosity liquids such as water, fuels and light chemicals.

Turbine Meter Features

High accuracy – suitable for batching and blending
Wide turndown – broad flow range
Pulse and analog outputs – connect to totalizers and controls
Sanitary and stainless versions – food and chemical service

Installation Tips

Provide enough straight pipe upstream and downstream, and install a strainer to protect the rotor. Viscosity changes affect accuracy, so turbines suit consistent, clean fluids.

Centro supplies turbine flow meters for water, fuel and chemical measurement.

Water Gauges

Water gauges show water level in boilers, tanks and pressure vessels. Clear, dependable level indication is critical for safe boiler operation.

Water Gauge Products

Gauge glass sets – tubular and reflex gauges
Gauge valves – isolate glass for replacement
Guard rods – protect glass
Replacement glass and packing – maintenance
Try cocks – backup level checks

Maintenance Tips

Blow down water gauges regularly and replace etched or cloudy glass. Use glass rated for boiler pressure and temperature.

Centro supplies water gauges and parts for boilers and tanks.

Related categories: Liquid Level | Level Sensors | Level Switches | Differential Pressure Control | Radar

Instrument/Compression Fittings

Compression fittings are used in a variety of industries for a multitude of applications. Compression fittings are most commonly used in applications where copper or brass tubing is inserted into the fitting. The ferrule then compresses the tubing, creating a watertight seal. Compression fittings can be found in everything from plumbing and refrigeration to automotive and aerospace applications. Our team is proud to offer a wide variety of compression fittings, ensuring that you'll find the perfect solution for your needs. Centro carries instrument and compression tube fittings in stainless steel and brass, along with tubing, valves and adapters to complete your instrument lines. Please browse our website to learn more about our products and services.

Related categories: Instrumentation, Measurement and Control | Sensors | Recorders | Analytical Tools | Controllers

Gauge Parts & Accessories

Gauge parts and accessories protect, mount and maintain pressure gauges. The right accessory improves accuracy and gauge life and makes installations safer.

Accessories Available

Syphons – protect gauges from steam
Snubbers – dampen pulsation
Gauge valves and cocks – isolation for service
Panel mounting kits and brackets – secure mounting
Overpressure protectors – prevent damage from spikes

Choosing Accessories

Match thread sizes and materials to your gauge and process, and select protective devices for the conditions.

Centro supplies gauge parts and accessories.

Related categories: Gauges | Tridicators | Pressure Gauges | Manometers | Tubular Gauges

Pressure Snubber

Pressure snubbers smooth out pressure spikes and pulsations before they reach gauges, switches and transmitters. Damping the surges gives steadier readings and helps instruments last longer, especially near pumps, compressors and quick-closing valves.

Snubber Types

Porous metal disc snubbers – sintered elements for gases and light liquids
Piston snubbers – self-cleaning action for dirtier fluids
Adjustable snubbers – tune the damping to your system
Brass and stainless steel – match media compatibility

Choosing a Snubber

Select the element grade based on fluid viscosity: finer discs for air and water, coarser for oils. Match thread sizes to your gauge and process connection. For very severe pulsation, combine a snubber with a liquid-filled gauge.

Centro carries pressure snubbers and gauge accessories to protect your instruments.

Related categories: Pressure Control Accessories | Manifold Valves | Gauge Cock Valve | Instrument Valve | Syphons

Manifold Valves

Instrument manifold valves mount between process piping and pressure or differential pressure transmitters. A manifold lets technicians isolate, equalize, vent and calibrate instruments without shutting down the process.

Manifold Types

2-valve manifolds – isolate and vent gauge and pressure transmitters
3-valve manifolds – isolate and equalize DP transmitters
5-valve manifolds – add vent and calibration ports for DP service
Direct-mount and remote-mount – fit your transmitter installation
Stainless and alloy bodies – for corrosive and high-pressure service

Choosing a Manifold

Match the manifold to the transmitter type and connection (flanged or NPT), and the process pressure and temperature. Choose hard or soft seats according to temperature and leak-tightness requirements. Integrated manifolds save space and leak points.

Centro supplies instrument manifold valves for pressure and DP transmitter installations.

Related categories: Pressure Control Accessories | Gauge Cock Valve | Pressure Snubber | Instrument Valve | Syphons

Analytical Tools

We carry a complete selection of analytical tools for purchase online. This includes everything from analytical probes and transmitters to conductivity probes. Industrial applications often require the use of Analytical Tools including Analytical Probes, Analytical Transmitters, and Conductivity Probes to measure various parameters. These probes can be used to measure things like pH, conductivity, temperature, and more. Each type of probe has its own unique benefits and drawbacks, so it's important to choose the right one for the job at hand. Analytical Probes are often used for measuring pH, as they are very accurate and precise. Analytical Transmitters are good for measuring conductivity, as they are able to transmit a signal over long distances. Conductivity Probes are often used for measuring temperature, as they are very sensitive to changes in temperature. When choosing a probe for an industrial application, it's important to consider the accuracy, precision, and sensitivity of the probe. Analytical Probes, Analytical Transmitters, and Conductivity Probes are all great choices for industrial applications, so it's just a matter of choosing the right one for the job. Whether you need a single piece of equipment or a complete set, we have you covered. We also offer a wide range of accessories so that you can tailor your purchase to your specific needs. And because our products come from leading manufacturers, you can rest assured that you're getting the highest quality tools on the market. So please browse our selection today and find the perfect analytical tool for your needs.

Shop by type: Conductivity | pH

Tridicators

Tridicators combine pressure (or altitude) and temperature readings in one gauge. They're standard on hot water boilers and hydronic heating systems.

Features

Dual readings – pressure and temperature
Altitude scale – feet of water for hydronic systems
Brass construction – water service
Standard connections – boiler tappings

Choosing a Tridicator

Select pressure and temperature ranges for the system, plus stem length and connection size. Replace gauges that read inaccurately.

Centro supplies tridicators for boilers and hydronic systems.

Related categories: Gauges | Gauge Parts & Accessories | Pressure Gauges | Manometers | Tubular Gauges

Anemometer Flow Meters

Anemometer flow meters measure air and gas velocity, and from that, airflow volume, in ducts, vents and open spaces. HVAC technicians, industrial hygienists and plant engineers use them for balancing, ventilation checks and dust collection troubleshooting.

Anemometer Types

Vane anemometers – rotating vanes for duct and grille readings
Hot-wire (thermal) anemometers – sensitive low-velocity measurement
Pitot tube meters – high-velocity and dirty air streams
Inline airflow transmitters – continuous duct monitoring
Multi-function meters – velocity, temperature and humidity in one tool

Choosing a Meter

Match the meter to your velocity range and where you'll measure, whether that's ducts, open faces, stacks or rooms. Hot-wire probes fit small holes but aren't suited to dirty or hot gas, while pitot tubes handle tougher conditions. Data logging and CFM calculations speed up reporting.

Centro carries anemometers and airflow meters for HVAC, ventilation and industrial air systems.

Sensors

Industrial sensors monitor humidity, gas, flame, moisture and dew point to protect people, products and equipment. They feed critical data to control and safety systems.

Sensor Categories

Humidity sensors – HVAC and environmental control
Gas detection sensors – toxic and combustible gases
Flame detection sensors – burner and fire safety
Moisture in oil sensors – lubrication and transformer monitoring
Dew point sensors – compressed air and gas dryness

Choosing a Sensor

Define what you need to measure, the range, accuracy and output signal, plus environmental and hazardous area ratings. Plan for calibration and maintenance.

Centro supplies industrial sensors for monitoring and safety applications.

Shop by type: Humidity Sensors | Gas Detection Sensors | Flame Detection Sensors | Moisture in Oil Sensors | Dew Point Sensors

Commercial Gauges

Commercial pressure gauges cover HVAC, plumbing, fire protection and general building services. They're economical, easy to read and available in many standard ranges.

Commercial Gauge Options

Dry and liquid-filled gauges – general service
Brass internals – water, air and oil
Common dial sizes – 2" to 4"
Bottom and back connections – line or panel mounting
Fire protection gauges – sprinkler system ratings

Choosing a Gauge

Select a range about twice normal operating pressure, and match connection size and dial type. Liquid-filled gauges handle vibration from pumps.

Centro supplies commercial gauges for HVAC, plumbing and building systems.

Instrumentation Needle Valves

Needle valves give fine, repeatable control of low flows in instrument lines, sampling systems and gauge isolation. A slender, tapered stem seats into a matching orifice, so a few turns of the handle let you dial in precise flow or shut it off completely.

Needle Valve Options

Straight and angle patterns – suit your piping layout
Hard-seat and soft-seat designs – metal seats for high temperature, PTFE or PEEK for bubble-tight shutoff
Bar stock and forged bodies – in 316 stainless steel, brass and carbon steel
NPT, tube and socket weld ends – connect directly to tubing or pipe
High-pressure models – rated to 6,000 psi and beyond

Selecting a Needle Valve

Consider the pressure and temperature rating, the flow coefficient (Cv) you need, and the media's compatibility with the body and packing. Choose regulating stems for throttling and standard stems for isolation. Panel-mount options and lockable handles are available for instrument panels.

Centro carries instrumentation needle valves in a wide range of sizes and materials for process, hydraulic and analytical systems.

Related categories: Instrumentation Valves | Instrumentation Check Valves

Electrical Accessories

Electrical accessories complete control panels and machines. Push buttons, signal devices, connectors, thermal management and cable systems let operators control equipment and keep panels running reliably.

Accessory Categories

Push buttons and control lighting – operator controls and indicators
Sounders – audible alarms
Connectors – reliable wiring connections
Thermal management – fans, heaters and air conditioners
Drag chain guide systems – protect moving cables
Transformer accessories – fuses and mounting

Choosing Accessories

Match accessories to your panel's voltage, environment and space. Consistent product families simplify spares and maintenance.

Centro supplies electrical accessories for control panels and machine builders.

Process Gauges

Process pressure gauges are built for chemical, petrochemical, refining and power plant service. Heavy-duty cases, stainless wetted parts and high accuracy give dependable readings in demanding environments.

Process Gauge Features

Solid-front safety cases – operator protection
316 stainless steel internals – corrosive media
Liquid filling – vibration and pulsation damping
Accuracy to 0.5% – precise readings
4.5" and 6" dials – easy reading

Choosing a Process Gauge

Choose range, accuracy, connection and materials suited to the process. Add diaphragm seals for corrosive, viscous or high-temperature media.

Centro supplies process gauges and accessories for plant instrumentation.

Test Gauges

Test gauges, also called calibration gauges, provide high-accuracy readings for checking and calibrating other instruments. They're essential tools for maintenance and instrument technicians.

Test Gauge Options

Analog test gauges – 0.25% accuracy with mirror dials
Digital test gauges – high accuracy and data logging
Wide range selections – vacuum to high pressure
Calibration certificates – traceable documentation

Choosing a Test Gauge

Select accuracy at least four times better than the instruments you're testing. Choose range and connection to match. Handle and store test gauges carefully to protect accuracy.

Centro supplies test gauges for calibration and verification.

Enclosures

Electrical enclosures protect control equipment from dust, water, chemicals and impact, and protect people from live components. The right enclosure is essential for safe, reliable control panels.

Enclosure Types

Standard enclosures – wall-mount, floor-standing and junction boxes
Custom enclosures – built to your dimensions and cutouts
Stainless and fiberglass – corrosion resistance and washdown
Accessories – back panels, locks, windows and thermal management

Choosing an Enclosure

Select the NEMA or IP rating for the environment, then size it for components with room for wiring and heat dissipation. Consider material, mounting and access needs.

Centro supplies standard enclosures for control panels, plus custom enclosures made to order by leading manufacturers.

Shop by type: Custom Enclosures | Standard Enclosures

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