The purpose of the pre-check is to check the gas cylinder pressure, adapter hose non-return valves, low gas whistle, BLUE pressure and Valve Open whistle.

1. BLUE Cylinder pressure

Set the DPX switch valve in DEEP position.

Connect a BLUE adaptor hoses to a gas cylinder and the second adaptor hose to the gas outlet.

Open and close the cylinder valve to pressurize the system.

Check that the gas cylinder has more than 200 bar.

1. BLUE Non-return valve

Open the bleed valve on the gas cylinder side slowly.

Check that the pressure does not drop. (Non-return valve OK)

1. BLUE low gas whistle

Open the bleed valve on the gas outlet side slowly.

Check that the BLUE low gas whistle sounds at approximately 55 bar. (BLUE low gas whistle OK)

1. BLUE pressure and VALVE OPEN whistle

Depressurize and disconnect the adaptor hose from the gas outlet.

Connect a RED adaptor hose to the gas outlet.

Open and close the BLUE cylinder valve to pressurize the system.

Check that the RED pressure gauge shows 75 bar. (BLUE pressure OK)

Check that the VALVE OPEN whistle sounds.

Depressurize and disconnect the RED adapter hose.

1. BLUE 2:nd Cylinder pressure and 2:nd non-return valve

Connect a second gas cylinder to the loose adapter hose.

Move the first adapter hose from the first gas cylinder to the gas outlet.

Repeat test instructions 1 to 3 above.

Depressurize and reconnect the first cylinder to the first adapter hose so that two cylinders are connected.

If further gas cylinders shall be used, test instruction 1 above can be used to check the cylinder pressure. The DPX can now be prepared for diving.