Differential pressure is applied to the bellows and mechanical linkage assembly. As pressure changes, the bellows and linkage assembly is mechanically coupled to the gauge indicator pointer. If equipped with a micro-switch, a cam mechanically linked to the bellows, rotates and triggers the micro-switch. The major components of the Model 105/106 are a two-piece body, bellows sensing element and over-pressure assembly, a torque tube assembly, a range spring and the gauge front assembly. Model 105/106 assembly is protected against over-range in either direction to the rated working pressure by a bi-directional relief valve. Powered by a test quality Bourdon Tube Assembly which is encapsulated in a high pressure chamber that is fitted with a pressure connection to the inside of the Bourdon Tube and a second connection to the pressure chamber. The Model 109 indicates the difference between the pressure applied inside the Bourdon Tube and the pressure inside the chamber. The output shaft of the gauge assembly is magnetically coupled through the solid wall of the pressure chamber to a sensitive jeweled pointer shaft in the dial housing outside the chamber. The magnetic coupling transmits the exact motion of the assembly to the pointer to give an accurate dial reading of the differential pressure. The Bourdon Tube Assembly is protected against over-range in either direction to the rated working pressure by a bi-directional relief valve.

0-5 PSID to 0-400 PSID Mid-West Instrument piston type gauges offer safe working Pressures up to 10,000 PSI Rugged construction Weather Proof design Common Applications: Filter and Strainer Monitoring Compressed Air Hydraulic Refrigerant Pump Performance Testing Heat Exchanger Pressure Drop Monitoring Valves, Chillers etc., and for local flow indication and control Gauge, Switch and Transmitter options

0-20” H2O to 0-100 PSID Safe working Pressures up to 3,000 PSI Rugged construction Weather Proof design Common Applications: Filter and Strainer Monitoring Compressed Air Hydraulic Refrigerant Pump Performance Testing Heat Exchanger Pressure Drop Monitoring Valves, Chillers etc., and for local flow indication and control Gauge, Switch and Transmitter options

0-10” H2O to 0-800” H2O Mid-West Instrument tank level type gauges handle safe working Pressures up to 1000 PSI Rugged construction Weather Proof design Common Applications: Pressurized Tank Level Monitoring Stationary Tanks – Horizontal or Vertical Tanker Transport For materials such as LOX, CO2, Ammonia, Nitrogen, Helium, Nitrogen Hydrogen and Argon Gauge, Switch and Transmitter Options

Over 30 Years of proven design in the field for use in Hazardous locations CSA, UL, IECEx Certifications LVD RoHS Compliant Certifications apply to the entire assy. as mandated by Hazardous Location Stds. 3-4 Unannounced inspections by CSA and UL per year Yearly ATEX audits See individual models for complete specifications

Mid-West Instrument differential pressure gauges are available with switches and relays to allow you to be alerted of process conditions and control process equipment at pre-set values. Learn about differential pressure switch and relay features below. Reed switch and relay technology Hermetically sealed switches for reliability Field adjustable set points Available in enclosures or clamp on style