United Electric H100-702 H100 Series Pressure Switch

The United Electric H100-702, also cataloged as the H100-702 Pressure Switch, operates as a dedicated hardware component for binary pressure threshold detection within industrial fluid and gas process loops. Configured for low-pressure sensing, the assembly converts physical process pressure against a diaphragm into mechanical force to actuate a single-pole double-throw switch element.

Hardware Specifications

Process Control and DCS Instrument Loop Integration

The mechanical switch housing integrates into remote automated infrastructures through a single SPDT dry contact circuit, ensuring complete channel-to-channel isolation from adjacent instrumentation lines. When wired to a host Distributed Control System (DCS) digital input card, the contact interface forms a dedicated loop that prevents voltage propagation between non-isolated instrumentation grounds. The physical separation of the internal snap-action mechanism isolates high-voltage AC or low-voltage DC signals from the local process boundary, minimizing electrical noise induction during threshold state transition events.

Frequently Asked Questions

Q: How is the process loop protected against variable contact chattering during marginal pressure transitions near the setpoint?

A: The hardware features a fixed mechanical deadband spanning 1 to 4 PSI. This physical hysteresis prevents repetitive contact state toggling when the process line pressure dwells or fluctuates marginally near the designated 3 to 100 PSI trip threshold.

Q: Does the 14-pin internal block support external voltage supply line termination for loop monitoring?

A: No. The H100-702 is a purely mechanical switch that requires no loop power or external supply voltage for internal operation. The physical terminals interface exclusively with the dry contacts of the SPDT switch block.

Field Installation Guidelines

• Pressure Port Engagement: Apply industrial-grade thread sealant to the 1/4 in NPTF male process pipe. Thread the fitting into the instrument body ensuring a minimum of 5 full threads of engagement to maintain process boundary integrity up to the rated 500 PSI overrange threshold.
• Mechanical Setpoint Stabilization: Adjust the internal setpoint using the mechanical mechanism under calibrated line pressure. Once set, verify that the tamper-resistant setpoint lock is completely engaged to prevent calibration drift caused by compressor or pump physical vibration.
• Conduit and Moisture Isolation: Position the electrical conduit entry downward during vertical or horizontal surface installation. This physical orientation prevents moisture condensation from collecting inside the enclosure on the dry contact terminals.
• Electrical Grounding Protocol: Connect an external bonding conductor from the local protective earth grounding network directly to the enclosure ground terminal, ensuring a low-impedance path to earth.