Instrumentation, Measurement and Control - Hyett
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...
We are proud to offer a wide selection of industrial seals and accessories for various applications. Our seals are from leading manufacturers with high-quality materials designed to provide long-lasting, reliable performance in demanding industrial environments. We offer various seal types, including O-rings, gaskets, and rotary shaft seals. Our O-rings are available in various sizes and materials, including nitrile, silicone, and fluoroelastomer. They are ideal for use in hydraulic and pneumatic systems, as well as in general-purpose applications. Our gaskets are also made from high-quality materials and are designed to provide a tight, reliable seal in various applications. They come in a wide range of standard sizes, and manufacturers can make special sizes to order. We also carry a wide selection of rotary shaft seals, which are used to seal the gap between a rotating shaft and a stationary housing. These seals help prevent leakage of lubricants and other fluids and are available in various styles and materials to suit different applications. In addition to seals, we also offer a range of accessories to help you install and maintain your seals, including lubricants, sealant, and installation tools.
Shop by type: Diaphragm Seals | Capillaries
Related categories: Instrumentation, Measurement and Control | Flow Control | Instrumentation Valves | Pressure Control | Controllers
Diaphragm seals protect pressure gauges, switches and transmitters from corrosive, viscous, hot or clogging process media. A flexible diaphragm transfers pressure through a fill fluid so the instrument never touches the process.
Diaphragm Seal Types
- Threaded seals – general-purpose protection
- Flanged seals – larger connections and higher pressures
- Sanitary seals – tri-clamp for food and pharma
- In-line seals – slurries and flowing media
- Capillary systems – remote mounting
Choosing a Seal
Select diaphragm material, fill fluid and connection for your process. Consider temperature effects and instrument range. Assemblies are often filled and calibrated as a unit.
Centro supplies diaphragm seals and can help you choose the right seal and fill fluid for your instrument.
Related categories: Seals and Accessories | Capillaries
$306.36
Subject to factory lead times
$268.63$292.00
Subject to factory lead times
$474.29
Subject to factory lead times
$306.36
Subject to factory lead times
$268.63$292.00
Subject to factory lead times
$474.29
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.