Instrumentation, Measurement and Control - Apollo Valves
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 Apollo Valves (2)
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
Related categories: Instrumentation, Measurement and Control | Temperature Measurement, Instrumentation and Control | Analytical Tools | PVF | Sensors
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.
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
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Engineered by Apollo, the 2120402 is a Bronze Water Gauge 1/2". This product serves professionals across HVAC, oil and gas, and industrial processing sectors. The 2120402 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and NSF standards.
$109.35$129.47
Available for Purchase
Subject to factory lead times
The Apollo 2120500 is a Bronze Water Gauge 1/2". This product serves professionals across oil and gas, fire protection, and industrial processing sectors. The 2120500 reflects Apollo's long-standing reputation for quality and innovation.
$234.77$277.97
Available for Purchase
Subject to factory lead times
The Apollo 2120501 is a Bronze Water Gauge 1/2". It is commonly found in commercial mechanical systems, industrial processing, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. This product meets relevant ASME and NSF standards.
$118.41$140.20
Available for Purchase
Subject to factory lead times
The Apollo 2120502 is a Bronze Water Gauge 1/2". Typical applications span fire protection, HVAC, and oil and gas environments. Apollo Valves is recognized globally for engineering products that meet strict performance standards.
$108.20$128.11
Available for Purchase
Subject to factory lead times
The Apollo 2120503 is a Bronze Water Gauge 1/2". This product serves professionals across industrial processing, commercial mechanical systems, and HVAC sectors. The 2120503 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and NSF standards.
$222.43$263.35
Available for Purchase
Subject to factory lead times
Engineered by Apollo, the 2120403 is a Bronze Water Gauge 1/2". It is commonly found in plumbing, commercial mechanical systems, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. It is designed to comply with applicable ASME and NSF requirements.
$226.68$268.39
Available for Purchase
Subject to factory lead times
Part number 2125000 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in commercial mechanical systems, fire protection, and marine applications. Apollo Valves is recognized globally for engineering products that meet strict performance standards. This product meets relevant ASME and NSF standards.
$250.54$296.64
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125001 is a Bronze Water Gauge 1/2". This product serves professionals across HVAC, plumbing, and oil and gas sectors. Apollo Valves is recognized globally for engineering products that meet strict performance standards. This product meets relevant FM and ASME standards.
$103.35$122.37
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125002 is a Bronze Water Gauge 1/2". It is commonly found in fire protection, oil and gas, and plumbing applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$117.12$138.67
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125003 is a Bronze Water Gauge 1/2". Typical applications span fire protection, marine, and HVAC environments. Backed by Apollo's commitment to quality, the 2125003 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$242.68$287.33
Available for Purchase
Subject to factory lead times
The 2125100 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in industrial processing, plumbing, and commercial mechanical systems applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$250.54$296.64
Available for Purchase
Subject to factory lead times
The 2125101 from Apollo is a Bronze Water Gauge 1/2". Typical applications span commercial mechanical systems, industrial processing, and fire protection environments. Backed by Apollo's commitment to quality, the 2125101 is built to perform under real-world conditions. It is designed to comply with applicable NSF and ASME requirements.
$103.77$122.86
Available for Purchase
Subject to factory lead times
The 2125102 from Apollo is a Bronze Water Gauge 1/2". This product serves professionals across oil and gas, commercial mechanical systems, and industrial processing sectors. Apollo Valves is recognized globally for engineering products that meet strict performance standards.
$116.96$138.48
Available for Purchase
Subject to factory lead times
The 2125103 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in plumbing, fire protection, and commercial mechanical systems applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards. It is designed to comply with applicable ASME and FM requirements.
$242.68$287.33
Available for Purchase
Subject to factory lead times
Part number 234010E from Apollo is a Water Gauge 1/2". It is commonly found in commercial mechanical systems, plumbing, and industrial processing applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The 2340100 from Apollo is a Water Gauge 1/2". Typical applications span plumbing, commercial mechanical systems, and industrial processing environments. Backed by Apollo's commitment to quality, the 2340100 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The 2340101 from Apollo is a Water Gauge 1/2". It is commonly found in oil and gas, industrial processing, and marine applications. Apollo products are trusted by engineers and specifiers worldwide.
$654.72$775.18
Available for Purchase
Subject to factory lead times
The 2340102 from Apollo is a Water Gauge 1/2". This product serves professionals across plumbing, oil and gas, and fire protection sectors. The 2340102 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and FM standards.
$839.75$994.26
Available for Purchase
Subject to factory lead times
The 2340103 from Apollo is a Water Gauge 1/2". Typical applications span fire protection, commercial mechanical systems, and marine environments. Backed by Apollo's commitment to quality, the 2340103 is built to perform under real-world conditions.
$1,832.38$2,169.52
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340200 is a Water Gauge 1/2". This product serves professionals across marine, plumbing, and commercial mechanical systems sectors. The 2340200 reflects Apollo's long-standing reputation for quality and innovation. It is designed to comply with applicable UL and FM requirements.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340201 is a Water Gauge 1/2". Typical applications span fire protection, HVAC, and plumbing environments. Backed by Apollo's commitment to quality, the 2340201 is built to perform under real-world conditions.
$655.26$775.82
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340202 is a Water Gauge 1/2". It is commonly found in HVAC, commercial mechanical systems, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. It is designed to comply with applicable ASME and FM requirements.
$840.50$995.14
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340203 is a Water Gauge 1/2". This product serves professionals across plumbing, commercial mechanical systems, and oil and gas sectors. The 2340203 reflects Apollo's long-standing reputation for quality and innovation.
$1,832.38$2,169.52
Available for Purchase
Subject to factory lead times
The Apollo Valves 2365100 is a Water Gauge 1/2". Typical applications span fire protection, marine, and HVAC environments. Backed by Apollo's commitment to quality, the 2365100 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$1,172.79$1,388.58
Available for Purchase
Subject to factory lead times
Engineered by Apollo, the 2120402 is a Bronze Water Gauge 1/2". This product serves professionals across HVAC, oil and gas, and industrial processing sectors. The 2120402 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and NSF standards.
$109.35$129.47
Available for Purchase
Subject to factory lead times
The Apollo 2120500 is a Bronze Water Gauge 1/2". This product serves professionals across oil and gas, fire protection, and industrial processing sectors. The 2120500 reflects Apollo's long-standing reputation for quality and innovation.
$234.77$277.97
Available for Purchase
Subject to factory lead times
The Apollo 2120501 is a Bronze Water Gauge 1/2". It is commonly found in commercial mechanical systems, industrial processing, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. This product meets relevant ASME and NSF standards.
$118.41$140.20
Available for Purchase
Subject to factory lead times
The Apollo 2120502 is a Bronze Water Gauge 1/2". Typical applications span fire protection, HVAC, and oil and gas environments. Apollo Valves is recognized globally for engineering products that meet strict performance standards.
$108.20$128.11
Available for Purchase
Subject to factory lead times
The Apollo 2120503 is a Bronze Water Gauge 1/2". This product serves professionals across industrial processing, commercial mechanical systems, and HVAC sectors. The 2120503 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and NSF standards.
$222.43$263.35
Available for Purchase
Subject to factory lead times
Engineered by Apollo, the 2120403 is a Bronze Water Gauge 1/2". It is commonly found in plumbing, commercial mechanical systems, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. It is designed to comply with applicable ASME and NSF requirements.
$226.68$268.39
Available for Purchase
Subject to factory lead times
Part number 2125000 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in commercial mechanical systems, fire protection, and marine applications. Apollo Valves is recognized globally for engineering products that meet strict performance standards. This product meets relevant ASME and NSF standards.
$250.54$296.64
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125001 is a Bronze Water Gauge 1/2". This product serves professionals across HVAC, plumbing, and oil and gas sectors. Apollo Valves is recognized globally for engineering products that meet strict performance standards. This product meets relevant FM and ASME standards.
$103.35$122.37
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125002 is a Bronze Water Gauge 1/2". It is commonly found in fire protection, oil and gas, and plumbing applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$117.12$138.67
Available for Purchase
Subject to factory lead times
The Apollo Valves 2125003 is a Bronze Water Gauge 1/2". Typical applications span fire protection, marine, and HVAC environments. Backed by Apollo's commitment to quality, the 2125003 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$242.68$287.33
Available for Purchase
Subject to factory lead times
The 2125100 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in industrial processing, plumbing, and commercial mechanical systems applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$250.54$296.64
Available for Purchase
Subject to factory lead times
The 2125101 from Apollo is a Bronze Water Gauge 1/2". Typical applications span commercial mechanical systems, industrial processing, and fire protection environments. Backed by Apollo's commitment to quality, the 2125101 is built to perform under real-world conditions. It is designed to comply with applicable NSF and ASME requirements.
$103.77$122.86
Available for Purchase
Subject to factory lead times
The 2125102 from Apollo is a Bronze Water Gauge 1/2". This product serves professionals across oil and gas, commercial mechanical systems, and industrial processing sectors. Apollo Valves is recognized globally for engineering products that meet strict performance standards.
$116.96$138.48
Available for Purchase
Subject to factory lead times
The 2125103 from Apollo is a Bronze Water Gauge 1/2". It is commonly found in plumbing, fire protection, and commercial mechanical systems applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards. It is designed to comply with applicable ASME and FM requirements.
$242.68$287.33
Available for Purchase
Subject to factory lead times
Part number 234010E from Apollo is a Water Gauge 1/2". It is commonly found in commercial mechanical systems, plumbing, and industrial processing applications. As a leader in valves and flow control, Apollo manufactures every component to exacting standards.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The 2340100 from Apollo is a Water Gauge 1/2". Typical applications span plumbing, commercial mechanical systems, and industrial processing environments. Backed by Apollo's commitment to quality, the 2340100 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The 2340101 from Apollo is a Water Gauge 1/2". It is commonly found in oil and gas, industrial processing, and marine applications. Apollo products are trusted by engineers and specifiers worldwide.
$654.72$775.18
Available for Purchase
Subject to factory lead times
The 2340102 from Apollo is a Water Gauge 1/2". This product serves professionals across plumbing, oil and gas, and fire protection sectors. The 2340102 reflects Apollo's long-standing reputation for quality and innovation. This product meets relevant UL and FM standards.
$839.75$994.26
Available for Purchase
Subject to factory lead times
The 2340103 from Apollo is a Water Gauge 1/2". Typical applications span fire protection, commercial mechanical systems, and marine environments. Backed by Apollo's commitment to quality, the 2340103 is built to perform under real-world conditions.
$1,832.38$2,169.52
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340200 is a Water Gauge 1/2". This product serves professionals across marine, plumbing, and commercial mechanical systems sectors. The 2340200 reflects Apollo's long-standing reputation for quality and innovation. It is designed to comply with applicable UL and FM requirements.
$1,851.35$2,191.99
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340201 is a Water Gauge 1/2". Typical applications span fire protection, HVAC, and plumbing environments. Backed by Apollo's commitment to quality, the 2340201 is built to perform under real-world conditions.
$655.26$775.82
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340202 is a Water Gauge 1/2". It is commonly found in HVAC, commercial mechanical systems, and marine applications. Apollo products are trusted by engineers and specifiers worldwide. It is designed to comply with applicable ASME and FM requirements.
$840.50$995.14
Available for Purchase
Subject to factory lead times
The Apollo Valves 2340203 is a Water Gauge 1/2". This product serves professionals across plumbing, commercial mechanical systems, and oil and gas sectors. The 2340203 reflects Apollo's long-standing reputation for quality and innovation.
$1,832.38$2,169.52
Available for Purchase
Subject to factory lead times
The Apollo Valves 2365100 is a Water Gauge 1/2". Typical applications span fire protection, marine, and HVAC environments. Backed by Apollo's commitment to quality, the 2365100 is built to perform under real-world conditions. This product meets relevant ASME and UL standards.
$1,172.79$1,388.58
Available for Purchase
Subject to factory lead times
FAQS
- 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.