Piston-type inline flow switch. IN and OUT on centerline. Reed switch closes on flow. Two 9/16-18 UNF ports — outlet requires accessory fitting. Kynar PVDF construction handles aggressive acids, halogens, oxidizers, and ultra-high-purity process fluids.
| Quantity | Price |
|---|---|
| 1–9 | $120.10 |
| 10–24 | $108.24 |
| 25–49 | $95.66 |
| 50–99 | $83.83 |
| 100–199 | $52.51 |
| 200+ | $47.74 |
The 5-21-KR is the straight body inline flow switch in Kynar PVDF for aggressive chemical and high-purity service.
| Specification | Value |
|---|---|
| Series | 5-21 |
| Body | Straight / Inline — IN and OUT on centerline |
| Overall Length | 3.65 in (92.71 mm) |
| Body Diameter | 0.75 in (19 mm) |
| Ports | 2× 9/16-18 UNF (outlet MUST have accessory fitting) |
| Switch | Hermetically sealed reed | SPST N.O. |
| Contact Rating | 70 VA / 50W | 0.5A AC / 0.7A DC |
| Voltage Max | 300 VAC / 350 VDC |
| Setpoints | 0.10 / 0.25 / 0.50 / 0.75 / 1.00 GPM |
| Lead Wire | 24 in (600 mm) |
| Compliance | RoHS |
| Material | Kynar PVDF |
The 5-21-KR 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-KR 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-KR 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.
Our engineering team can verify compatibility with your application and chemistry before you order.