Instrumentation, Measurement and Control - Marsh Bellofram
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...
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.
Related categories: Pressure Gauges | Test Gauges | Process Gauges | Differential Pressure 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.
Related categories: Pressure Gauges | Process Gauges | Commercial Gauges | Test Gauges | Differential Pressure 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.
Related categories: Pressure Gauges | Commercial Gauges | Industrial Gauges | Test Gauges | Differential Pressure Gauges
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
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.
Related categories: Pressure Gauges | Differential Pressure Gauges | Commercial Gauges | Digital Gauges | Process Gauges
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.
Related categories: Temperature Measurement, Instrumentation and Control | Temperature Regulators | Temperature Transmitters | Temperature Sensors | Temperature Recording
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
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
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
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.
Shop by type: Boiler Gauges | Manometers | Pressure Gauges | Gauge Parts & Accessories | Tridicators
Related categories: Pressure Control | Pressure Switch | Pressure Control Accessories | Pressure Transmitters | Pressure Transducers
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.
Shop by type: Pressure Transducers | Pressure Control Accessories | Gauges | Pressure Switch | Pressure Transmitters | Pressure Regulators | Sequence Valves
Related categories: Instrumentation, Measurement and Control | Controllers | Flow Control | Recorders | Seals and Accessories
$4.13
Subject to factory lead times
$4.13
Subject to factory lead times
$4.13
Subject to factory lead times
$4.42
Subject to factory lead times
$32.85
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$223.63$347.15
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$4.13
Subject to factory lead times
$4.13
Subject to factory lead times
$4.13
Subject to factory lead times
$4.42
Subject to factory lead times
$32.85
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$223.63$347.15
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
$340.95
Subject to factory lead times
- 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.
- 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.
- 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.
- 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.
- 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.