Many industrial processes involve the removal of air/gas from a pressurized liquid. ASVIN air vents are ideally suited for this purpose. The float-operated design means the vents can instantly and automatically adjust to variations in gas flow and pressure. The air vents can handle gas removal from liquids with specific gravities as low as 0.40 and pressure to 2,700 psi (186 bar). ASVIN air vents are available in a wide variety of sizes, end connections and construction materials.

Applications for ASVIN float-type air vents include hydronic heating systems, water service lines, water storage tanks, centrifugal pumps, gas lines, solvent filters and similar equipment. Operation is completely automatic, and the simple design and quality mechanism make operation trouble-free and maintenance infrequent.

Air can accumulate in remote sections of chamber-type heat-transfer equipment such as jacketed kettles, retorts, vulcanizers and jacketed sterilizers. ASVIN offers thermostatic air vents for positive venting of air and other non-condensable gases in such equipment.

Liquid Drainers

Provision for automatic drainage is sometimes not included in the original system. It is possible to discharge liquid manually through a valve that has been cracked open. However, an open drain also continuously wastes air or gas. Periodically opening a valve by hand and leaving it until it blows freely will also drain a system. Frequently, however, an operator will delay or forget to close a valve, thereby wasting precious air or gas.
Liquid drainers go by many names.

They are also known as
• Compressed air drains
• Condensate drainers
• Air traps
• Water traps
• Dump valves
• Float traps
• Compressed air traps

Liquid drainers installed at appropriate points will remove liquid continuously and automatically without wasting air or gas. In addition to drainage of the system, liquid drainers should provide:

• Trouble-free operation with minimal need for adjustment or maintenance
• Reliable operation even in the presence of dirt, grit and oil
• A long operating life
• Minimal air loss
• Ease of repair


 Separators, tanks with steam blankets, produce additional liquid as the steam condenses.

The 313 Overflow Trap traps and relieves this condensate and overflow without the steam blanket escaping. Buoyancy of its float ball provides force to operate internal valve assembly to relieve condensate and overflow to drain. Features steel chamber, brass/bronze internal valve,

316 stainless steel float ball.

Sizes 1” through 2” with NPT connections, and 3” through 6” with 150FLG

Large end cover provides easy access to internal valve assembly.

Cover can be tapped for optional sight glass assembly.

Optional sight glass assembly is available complete with brass ball check, shut-off valves, and drain valves.


As condensate/overflow enters the overflow trap the level of the liquid in the float chamber increases. For small amounts of liquid the float ball lifts the pilot assembly away from the piston disc and the liquid is relieved through the hole in the center of the piston disc. For large volumes of liquid the piston disc lifts off its seat in the valve body. The liquid then passes under the piston disc to the drain.

Installation         The overflow trap should be installed in an upright position.


The inlet and outlet of the overflow trap must be kept unblocked. The internal valve assembly must be kept free of debris, deposits, and dirt. The internal valve assembly should move freely.

Pressure – Temperature Rating

System operating pressures to 50 PSIG

Pressure drops to 15 PSI Approximate Shipping Weights

Temperatures to 250F

Nominal leakage rate 0.1% of rated capacity


TANK BLANKETING VALVES                       GAUGE HATCHES                                   VACUUM BREAKERS