5-21 — Straight Body Flow Switch

The 5-21 is used for pump start/stop control, high-level overflow protection, low-level dry-run protection, and tank or reservoir level alarms in OEM equipment. The modular ERECTA SWITCH system is built into laundry, HVAC, water-treatment, hydraulic, and chemical-handling machinery.

Choose the material to match the media: Polypropylene (PP) for general aqueous, acids, and bases; Acetal (AC/Delrin) for solvents, fuels, and hydrocarbons; Kynar PVDF (KR) for aggressive or harsh chemicals. Every ERECTA SWITCH model is offered in all three materials.

The 5-21 uses a magnetic reed switch wired in series with your relay or controller. Contact rating is 70 VA / 50 W resistive (UL File E70063). The switch ships with lead wires — connect directly to your control circuit.

No. The 5-21 is a mechanical float actuating a sealed reed switch — there is nothing to calibrate or power. This is a reliability advantage over electronic sensors that can drift over time.

Inspect that the float moves freely (check for debris or scaling), then test reed continuity with a multimeter. Because ERECTA SWITCH is modular, you replace only the individual component — switch, float, connector, or fitting — instead of the whole assembly.

Series 10 level switches are rated to 100 PSI; Series 5 flow switches to 200 PSI. Operating temperature depends on the housing material — Polypropylene, Acetal, and Kynar PVDF each have different thermal limits. Contact Compac engineering for your specific conditions.