United Electric, USA H100-172 PRESSURE SWITCH

Overview

The United Electric H100-172 pressure switch is a low-range industrial unit covering an adjustable set point range of 2 to 50 psi, ideal for low-pressure alarm, interlock, and control duties. Its tight dead band of 0.1 to 1.5 psi provides precise switching for sensitive processes where small pressure changes are significant.

Manufactured in the USA by United Electric Controls, the H100-172 features 316L stainless steel wetted parts and a 1/2 inch NPT female connection. With a proof pressure of 1000 psi, it offers exceptional over-range robustness for a low-range instrument.

Engineering & Design

The sensing element is configured for sensitive low-pressure detection while the precision snap-action switch delivers clean, repeatable contact transfer. The generous proof pressure rating of 1000 psi protects the element during system upsets and commissioning, reducing the risk of damage in real-world plant operation.

Housed in the standard H100 series Type 4X die-cast aluminium enclosure, the switch is sealed against weather and corrosion. The 1/2 inch NPT female connection accommodates larger-bore impulse lines commonly used in low-pressure services, while the 15A electrical rating provides ample margin for control circuits.

Key Features

• Adjustable set point range 2 to 50 psi
• Tight dead band 0.1 to 1.5 psi
• Proof pressure 1000 psi with 500 psi max over range
• 316L stainless steel wetted parts
• 1/2 inch NPT female pressure connection
• Type 4X certified die-cast aluminium enclosure
• 15A @ 125/250/480 VAC resistive electrical rating
• Ambient temperature -40°C to 71°C
• Sensitive low-pressure sensing design

Applications

• Low-pressure alarm and interlock systems
• Filter differential and pressure-drop monitoring
• Low gas pressure protection
• Air and inert gas systems
• Tank blanketing and pad pressure control
• Instrument air low-pressure alarms

Specifications

Low-pressure systems demand instruments that can detect small changes reliably without false alarms, and the United Electric H100-172 pressure switch delivers this through a tightly controlled dead band of 0.1 to 1.5 psi. This sensitivity makes the H100-172 suitable for duties where pressure variations of less than two psi must trigger a positive response.

For sensitive low-pressure duties, the United Electric H100-172 pressure switch is the dependable option, and Seven Star LLC supplies it with installation guidance.

The United Electric H100-172 pressure switch provides the pressure set point for the alarm and the shutdown circuits of the compressor stations. The unit is mounted with the bracket on the panel or directly on the process line, and the set point is verified with the local gauge before the commissioning. The NEMA 4X enclosure protects the contacts from the washdown and the outdoor condition.

The H100-172 unit is frequently used as the low pressure cutout of the compressor package, where the switch trips the machine on the suction pressure drop. The switch is wired in series with the control relay and the trip state is latched by the starter logic. The connection of the air line is made with the tubing adapter and the leak test is performed after the installation.

Why Seven Star LLC

Seven Star LLC supplies the United Electric H100-172 pressure switch with verified specifications and responsive service, helping engineers select low-pressure instruments that deliver dependable alarm and control performance. We support both new installations and maintenance spares programmes.

Based in Oman, we serve industrial customers across the GCC with reliable delivery and clear documentation.

Low-Pressure Engineering

The sensing element of the H100-172 is tuned for low-range measurement while the mechanical linkage preserves the positive snap action expected from the H100 series. The 1000 psi proof pressure is exceptional for a 2 to 50 psi instrument, giving plant operators confidence that the switch will survive process upsets without recalibration.

The 1/2 inch NPT female connection suits the larger impulse lines commonly installed on low-pressure systems, and the 316L stainless steel wetted parts maintain compatibility with clean and mildly corrosive gases.

Confirming the Model from the Nameplate

United Electric H100 switches carry the full model number on the nameplate, and the model code defines the range, wetted materials and options. When replacing an installed unit, read the complete code and compare it with the order, and note the set point, whether it acts on rising or falling pressure, and the contact configuration used in the control circuit. A replacement with the same model number keeps range, connection and wetted materials identical.

Set Point Adjustment and Calibration

Set the switch on a test bench with a calibrated pressure source rather than on the live process. Apply pressure slowly and note the actuation point, then reduce pressure to find the reset point; the difference is the dead band. Adjust the set point according to the manufacturer’s instructions until the switch operates at the required value on the correct direction of pressure change, and record the as-left values. Because this is a low-range instrument, use a test gauge with suitable resolution for the 2 to 50 psi range.

Maintenance and Troubleshooting

• Operates at the wrong point – verify with a test gauge, since set points can shift after impact or long service
• Nuisance alarms – pressure pulsation near the set point; consider a snubber or review the set point margin
• No change of state – blocked impulse line, closed isolation valve, or a wiring fault
• Moisture in the enclosure – check the cover seal and conduit entry sealing

Applications in Oman and the GCC

In the region the United Electric H100-172 pressure switch suits instrument air headers, low fuel gas pressure trips, tank blanketing systems and compressor suction protection, where a simple, robust electromechanical device provides an independent alarm or trip. The Type 4X enclosure handles outdoor installation, although switches in direct sun should be shaded to stay within the rated ambient temperature.

Request a Quote for United Electric, USA H100-172 PRESSURE SWITCH

For the United Electric H100-172 pressure switch, low pressure switch or any related control and instrumentation requirement, contact the Seven Star LLC team. Submit a formal inquiry through our RFQ page with your set point, range and connection requirements, and our specialists will respond with a detailed commercial proposal and the official United documentation.

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