Choosing the Proper Regulator
What type of gas and purity will you be using the equipment with?
The type of gas will dictate the inlet connection (CGA Fitting). The purity of the gas will dictate the internal materials of construction needed. Lower purity gases can be dispensed over neoprene diaphragms (Economy regulators), higher purity gases (UHP) must have regulators that have stainless steel diaphragms and PTFE seats (General Purpose and High Purity series).
Model Recommendations Chart
What is your desired delivery pressure?
Regulators have delivery ranges. Using a regulator that is not properly balanced for the desired delivery pressure will result in poor pressure control performance. The regulator should be balanced so that the desired delivery pressure is at about the midpoint of the regulators range.
Desired Delivery Pressure of 10 psi – Choose a regulator that will deliver between 0-25 psi
Desired Delivery pressure of 50 psi – Choose a regulator with a range of 0-125 psi
What are you connecting the regulator to?
The proper outlet connection will help you make a leak free connection to your tubing. Compression fittings are used for copper and stainless steel tubing. Hose barbs are normally used for plastic tubing. Trying to interchange these connectors usually leads to leaks.
Common Facts about Gas Regulations Equipment
Single-Stage vs. Two-Stage
Two-stage regulators control pressure better and don’t cost much more. Single stage regulators tend to increase delivery pressure as cylinder pressure decreases (not much though). Most equipment manufacturers recommend two-stage regulators.
Brass vs. Stainless Steel
Brass regulators are acceptable for Ultra- high purity applications. Stainless steel bodies do not make regulators cleaner in regards to the gas flow. Stainless steel diaphragms are used in all high purity regulators regardless of their body material. Stainless Steel body regulators are needed for corrosive gases and harsh external environments.
If the gauge shows 200 lbs, why won’t it deliver to 200 lbs?
Regulators have springs inside that control the maximum delivery pressure possible. The gauge does not dictate the maximum delivery pressure.
Can I dial in 2 psi when the gauge goes all the way up to 200 psi?
Not reliably. The regulator will actually fluctuate greatly if the range is too high. It will probably flow gas, but the pressure will not be stable.
Will my regulator control gas Flow?
Not well. Pressure regulators control pressure not flow. A flow valve will be needed to control flow.
Why does my gas regulator hum sometimes?
Regulator hum indicates that the seat and stem dampers are worn or inoperative. It is also possible that you are using an improperly ranged regulator.
Can I use any old regulator for my application?
Don’t go into that drawer full of old regulators and assemble a regulator that fits. Gas cylinders have up to 2400 psi of pressure. Accidentally putting a CGA fitting into a line regulator will result in a serious problem. Get the right regulator for the job or at least contact the manufacturer of the “old drawer dinosaur” and have them tell you it will be OK for you intended application. Changing a regulator from one service to another is also risky business.
Does CO2 require a washer
Yes, a small nylon or teflon washer is required for CGA 320 (CO2). If the washer is not present or severely deformed, the connection will leak.
Do I need to use teflon tape for my cylinder to regulator connection?
No, all cylinder connections are designed to connect without the use of teflon tape. Some connections use washers (320, 330, 660) , but most connections use metal-to-metal contact to form a leak free connection. The use of teflon tape is not necessary.
How tight should my cylinder connection be?
Tight enough not to leak. If the connection keeps leaking, check for damage to the face of the CGA fitting or debris in the cylinder valve connection. A washer could be missing as well (320, 330, 660).
When I turn the knob counter-clockwise (reduce pressure) on my regulator the delivery pressure does not change?
Most laboratory regulators are designed to be non-self relieving. The regulator will not reduce it’s delivery pressure unless the gas is flowing through the regulator. If the downstream segment of the system is static, the pressure will not drop unless you vent the system. However, the pressure will increase if you dial in a higher pressure when the system is static.