Mid-West Model 121 Piston Type Differential Pressure Gauge, 5 – 100 PSID

ABLE Instruments are Mid-West Instrument’s Official Representative for Sales and Service in the UK and Ireland, including the Model 121 Piston Type Differential Pressure Gauge (0-5 to 0-100 PSID or equivalent). The Mid-West Instrument Model 121 Piston Type Differential Pressure Gauge is an adaptable and precise solution for a variety of demanding differential pressure (DP) applications. This gauge is equipped with a terminal strip interface, simplifying electrical installations for switches or transmitters. Additionally, it offers the option to include a 4-20 mA transmitter for applications that require continuous remote monitoring. With a full-scale accuracy of ±3/2/3% and differential pressure dial scales ranging from 0-5 PSID to 0-100 PSID, the Model 121 ensures accurate and reliable readings.

Designed with a rugged piston-type sensing element, the Model 121 features a glass-reinforced thermoplastic dial case that is both panel mountable and weather-resistant. An anodized aluminium dial case option is also available. The gauge is built to withstand harsh environments, offering corrosion resistance, a shatter-resistant lens, and over-range protection for both high and low pressures. Its versatility is further enhanced by the availability of various switch and transmitter options, all supported by a terminal strip interface for ease of installation.

Features:

• Durable piston-type design sensing element.
• Glass-reinforced thermoplastic dial case, panel mountable (an anodised aluminium dial case option is available; contact sales for more information).
• Resistant to weather and corrosion.
• Shatter-resistant lens.
• Over-range protection for both high and low ranges.
• Switch and transmitter options with a terminal strip interface.

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The Model 121 supports multiple dial sizes, including 2-1/2”, 3-1/2”, 4-1/2”, and 6” diameters, and can be configured for both uni-directional and bi-directional scales. It operates effectively in temperatures ranging from -40°F to +200°F (-40°C to +93°C) and can manage working pressures up to 6000 PSIG (400 bar). Constructed from durable materials such as aluminium and 316/316L stainless steel, the gauge also features internal wetted parts made of 316 stainless steel and ceramic.

Common applications for the Model 121 include filter and strainer monitoring, compressed air systems, hydraulic systems, refrigerant monitoring, pump performance testing, and heat exchanger pressure drop monitoring. With its robust design, accurate measurement capabilities, and ease of installation, the Model 121 is a reliable choice for various industrial needs. Contact us today for availability and further information.

What are the electrical switch specifications? Mid-West Instrument switches feature mechanical adjustability, allowing customers to set the switch within a specified adjustment range of the instrument. All configurations come with a ½” FNPT conduit interface. Additionally, Mid-West can preset switch set points upon customer request. All switches are CE marked in accordance with the EU Low Voltage and RoHS Directive.

The Mid-West Instrument 121 is a differential pressure transmitter, available in both indicating and non-indicating versions. It is a 2-wire loop-powered microprocessor-based transmitter that outputs a 4-20 mA signal. Utilising a magnetic angle sensor, it detects the angle of the magnet, which moves linearly within the bore relative to the transmitter sensor. Each transmitter undergoes an individual 11-point calibration linearisation process to ensure accuracy. CE marking for RoHS and EMC Directive compliance is available upon request.

These switches do not require power to operate and can be configured with one or two independently adjustable switches. The 4-20 mA transmitter operates on 8-28 VDC loop power with 2% accuracy (20%-100% of scale, ascending). Various switch output options are available, including:

• SPDT 3W, 0.25 Amp, 125 VAC/VDC
• SPST 60W, 3.0 Amp, 240 VAC/VDC (Normally Open)
• SPST 60W, 3.0 Amp, 240 VAC/VDC (Normally Closed)
• SPST 60W, 3.0 Amp, 240 VAC/VDC (1 Normally Open, 1 Normally Closed)

Additional features include a field-wirable terminal strip, switches CE marked for Low Voltage and RoHS Directives, weather-resistant electrical enclosures (NEMA 4X), and options for hazardous locations, including Class I Division 2 (Groups A, B, C, D) and Class II Division 2 (Groups F & G). Both the transmitter and switch options are available, with complete assemblies third-party certified.

Model 121 Specifications: