Longfor Enterprises Inc.

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Our Valves--Renovated Design

In order to obtain reliable data for gas/vapour sample evaluation, not only gas sampling bag material, but also the valve on the bags plays important role.

A good fitting and valve should have the following properties: inexpensive, reliable, easy to install, easy to use, chemically stable, and not introducing contaminants.

combo alve stainless valve ssvalve o-ring

Pictures: Common valves used in the market

Most fittings or valves used in gas sample bags are metal or plastic and have screws on the body, which is allowed to accept a nut to secure the fitting/valve with the film. The drawbacks of this type of fitting/valve are: the screws on meal fitting have to be machined, production cost is high; slow assembly process and low efficiency, the nut has to be installed by turning it to the bottom of fitting and secure it on the film; it may produce uneven or crease film surface between bottom of fitting and the nut, it may cause potential leakage. Some types of valve/fitting have on/off function, since it has screw design, it has to turn many rounds to open or close the valve/fitting. Most of fittings use an O-ring inside fitting to prevent leakage. The O-ring may cause contamination and lead inaccurate analytical results.

pc staight valve

PC straight valve


PC side opening valve

ptfe side opeing valve

PTFE side opening valve


PTFE straight valve

Pictures: Our Patented Valves


Our valves are made of high quality, medical grade Polycarbonate (PC) or Polytetrafluoroethylene (PTFE). Both PC and PTFE valves are produced by precision moulding technology. The body of valves contacts with plug perfectly so that they are sealed itself, there is no need O-ring or sealant to prevent leaking. The body of valve has locking mechanism, once the plug was assembled, it is locked to the body of valve and can't be pulled out or loose. Compared to metal valves or fittings, plastic valves are light weighted.

PC valve is made of high quality medical grade polycarbonate. Polycarbonate is stronger and usable over a greater temperature range. The PC valve operating temperature should be less than 60 C. PC is chemically resistant to most chemicals. There are two variants of PC valves, one type is that the connector is vertical to bag film and another one is parallel. Both have the same functionality. The valve has on/off function, flow rate control and cap for sampling.

PTFE valve has superb chemical inertness, it can meet your various applications. Operating temperature should be less than 100 C. High temperature may have adverse impact of sealing property and cause leaking. The valve has on/off function, flow rate control and cap for sampling.

The valve is easy to use. When the handle is aligned with the connector in any direction, the valve is in open position for filling samples or withdrawing sample by syringe. When the handle is in 90 degree position to the connector, the valve is closed. The valve can control flow rate by turning angles between 0-90 degree. This is one of advantages, you don't need to turn many turns like other valves in the market to open or close the valve. All our valves are integrated with sampling cap with silicone septum. Another advantage is that the gas between sampling cap and plug can be released by loosing the cap after the bag is filled with sample so that the gas sample in the bag does not contact the septum. It can keep integrity of the sample and minimize the potential contamination by septum.

Our design was patented and any infringement of the intellectual property will be prosecuted.