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Check Valve

  1. Disconnect hose to check valve at bypass valve. Connect a suitable squeeze bulb tester to hose.
  2. Squeeze bulb to force as much air from bulb as possible. Quickly release bulb and start timing. The bulb should remain collapsed (not returning to its original shape) for at least 15 seconds.
  3. If bulb returns to its original shape within 15 seconds, check bypass hose to ensure that it is free of leaks. If hose is in good shape, replace check valve.