Check Valves for Metering & Dosing Pumps

Chemical metering and dosing pumps live or die by their check valves. A metering pump uses check valves on the suction and discharge to turn each stroke into net flow in one direction, so when a check fouls, leaks, or picks the wrong material, dosing accuracy falls apart and chemical can siphon back. This is the corner of the catalog Apex knows best.

Why metering pumps need the right check valve

Each pump stroke draws chemical in past the suction check and pushes it out past the discharge check. If a check leaks back, the pump loses volume and the dose drifts. If it sticks, the pump loses prime. And because the fluid is often aggressive, the wrong seal fails fast. Precision and chemical compatibility both ride on these small valves.

Match the material and seal to the chemical

  • Sodium hypochlorite (chlorine), acids, most water-treatment chemicals - PVC or 316 stainless body with a Viton (FKM) or PTFE seal. See the sodium hypochlorite piping guide.
  • General water dosing - 316 stainless with Viton, or PVC.
  • Avoid - brass and Buna-N on chlorine and aggressive chemicals; they degrade.

Full seal detail in the Valve Seat Material Guide, and body choice in Material Selection.

Size to the tubing, not oversize

Metering checks are small (typically 1/8 in. to 1/2 in.) and should match the pump connection and tubing. Oversizing causes chatter and lost accuracy; the valve should be sized so each stroke fully cycles it. Inline and spring styles suit the fast, low-volume cycling of a metering pump.

Consider a double check for extra assurance

Where back-siphoning of chemical would be a safety or accuracy problem, a double check valve (two elements in series) adds redundancy. See the difference in Double Check vs Check Valve.

Common metering-check failures

Dose drift usually means a check leaking back; loss of prime means a stuck suction check or air lock; rapid seal failure means a material mismatch. The steps are in Check Valve Troubleshooting.

Shop metering-pump check valves

Browse the metering pump check valves collection, or the broader inline and spring checks in 316 stainless and PVC. Building a full dosing skid? The selection guide ties it together.