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Pressure Regulators

Operation & Handling


Be certain that the materials of a pressure regulator are chemically compatible with the intended gas service before installation. Inspect the regulator for the proper CGA inlet connection and note the ranges of the pressure gauges. Also examine the physical condition of the regulator including its threads and fittings. Remove any dust or dirt from the regulator or cylinder valve with a clean cloth. Do not install a regulator on a cylinder valve containing oxygen or another oxidant if grease or oil is present on either. Such combustible substances in contact with an oxidant are explosive. Initiate procedures to have the equipment properly cleaned and identify the equipment to prevent usage.


The regulator should be securely installed on the cylinder valve using the proper wrench and without forcing the connection. Do not use pipe dope, pipe thread or Teflon® tape on valve connections, and never use valve connections that leak. The regulator adjusting knob should be turned in the full counterclockwise or closed direction. Most Scott regulators are equipped with a needle valve in the regulator output. This should be adjusted to the full clockwise direction. The downstream equipment connection can then be made to the regulator output needle valve.


The operator, protected by safety glasses, should stand to the side of the cylinder opposite the regulator and slowly open the cylinder valve until the high-pressure gauge indicates the full cylinder pressure.

The regulator output needle valve can be opened after it is certain that all downstream equipment is ready.

Open the regulator by turning its adjustment knob clockwise until the desired output pressure is indicated on the delivery gauge. After this setting is made, inspect the delivery pressure gauge to make certain that the regulator is providing a constant and stable output pressure.

Check the system for leaks by closing the downstream equipment valve, setting regulator pressure, closing the cylinder valve and turning the regulator adjusting knob one turn counter-clockwise. A decrease in the high-pressure gauge will indicate a leak in the cylinder valve inlet fitting or high-pressure gauge. A decrease in the low-pressure gauge indicates a leak in the outlet fitting, low-pressure gauge or a downstream equipment connection. Check for the exact location by using appropriate leak detection instrumentation or methods. A decrease in the high-pressure gauge occurring concurrently with an increase in the low-pressure gauge indicates a leak in the regulator seat. The regulator must then be repaired or returned to Scott for servicing.

Close the cylinder valve when the cylinder is not in use. When the downstream equipment is not being used, close the cylinder valve and open the equipment valve to relieve all pressure from the regulator. Close the equipment valve and then release all tension on the regulator adjusting knob by turning it in the full counter-clockwise direction.

Removing the Regulator from Service

Close the cylinder valve fully and isolate the regulator by safely removing all gas. Consideration must be given to the type of gas in service and the safe removal of residual gas from the regulator or equipment. With no gas pressure in the regulator, remove all tension on the regulator adjusting knob by turning it in the full counterclockwise direction. Remove the regulator from the cylinder valve by using the proper wrench and protect it from damage and foreign materials. Install the protection cap on the cylinder valve.