Valves

Originally Published April 2000

SPOTLIGHT

Valves

Pinch valves

High-flow pinch valves are suitable for applications requiring high purity, zero dead volume, or particulate handling. The S-line of valves includes two-way normally closed, two-way normally open, and three-way universal constructions and can handle tubing sizes ranging from 1/16 to 3/8 in.in. The valves' long stroke allows the silicone tubing to open fully, providing maximum fluid flow while preventing particulate from becoming trapped, according to the manufacturer. A magnetic latching version is available for low power consumption and prolonged coil life. Automatic Switch Co., 50-60 Hanover Rd., Florham Park, NJ 07932.
 

Dispensing valves

A series of dispensing valves is suitable for dispensing very difficult, high-viscosity, and stringy materials that have short pot lives. The 340-series valves can dispense thin, low-viscosity materials where positive displacement is required. Features of the valves include an adjustable displacement volume control; a completely disposable wetting system; a programmable, microcontroller-operated electronic sequencing system; and automatic and adjustable suck-back. Different versions can dispense between 0.001 to 1.0 cm³ of fluid, depending of the model. Tridak, A Div. of Indicon Inc., 2686 Buckner Ave., #B, Ft. Meade, MD 20755.
 

High-pressure valves

Capable of continuous operation to 10,000 psi, a series of high-pressure pneumatically operated valves is supplied with small, electrically operated pilot valves. CV valves can be supplied with fittings for either 1/8- or 1/4-in. high-pressure tubing, and can be placed in ovens. Solenoid-actuated pilot valves can be either manually operated or computer controlled. On-off and three-way, four-position valve combinations are available. All models are made with corrosion-resistant stainless steel or Hastelloy C-276. Vindum Engineering Inc., 1 Woodview Ct., San Ramon, CA 94583.
 

Pinch valve

Using a motor-driven cam coupled with a position-sensing rotary switch, a dual-channel pinch valve requires a fraction of the power used by traditional solenoid pinch valves. The PV256 valve consumes approximately 0.4 W during the 300-600-millisecond transition from state to state. It consumes no power and generates no heat in its three pinched states. The valve measures 2.3 x 0.7 x 0.6 in. and accepts 1/8-in.-OD and 1/16-in.-ID tubing in a variety of materials. External control circuitry is required. Instech Laboratories Inc., 5209 Militia Hill Rd., Plymouth Meeting, PA 19462.
 

Needle-free valves

Swabbable, needle-free valves feature a spring-loaded split septum and can be accessed with any male luer, such as a syringe or IV adapter. The male adapter opens the NFV-3 valves and allows bidirectional flow. The valves automatically close when the male luer is removed, preventing backflow of fluids. The valves are designed for applications that require needle-free intermittent injection, aspiration, or infusion of fluids. They are available in Y and in-line configurations. Burron OEM Div., B. Braun Medical Inc., 824 Twelfth Ave., Bethlehem, PA 18018.
 

Relief valves

Miniature plastic relief valves are preset to spring pressures between 0.25 and 10 psi. End fitting combinations available include 10-32 female and 10-32, 1/4-in.-28, and 1/8-in. male. Standard valves are equipped with Buna O-rings with a stainless-steel spring and polypropylene body, and Viton O-rings and nylon body materials are also available. For larger flow sizes, 1/4- and 3/8-in. male and 1/8-in. and 1/4-in. female fittings can be ordered. Industrial Specialties Manufacturing Inc., 2741 S. Wadsworth, Ste. 315, Lakewood, CO 80232.
 

Servo valves

Servo valves provide precise proportional control of fluid pressure and flow. The valves combine a torque motor with a frictionless nozzle flapper, shear orifice, or jet pipe valve. The input signal can be either voltage or current, and the output is a precisely controlled stepless flow rate or pressure. The valves are suitable for use in piloting larger valves, providing servo control of actuators, and in fluid pressure and flow control applications. Woodward HSC Inc., 390 Youngs Rd., Buffalo, NY 14221.
 

Microdispensing valve

Designed for applications where size, dispense volume, and repeatability are important, a 1200-Hz, two-way solenoid valve can be placed directly over the individual well centers of standard 96-well microtiter plates. The 0.22-in.-diam VHS valve is available with either a 0.05-in.- or 0.02-in.-diam outlet port or a jeweled orifice for direct dispensing. The valve consumes 500 mW maximum power and has a 200,000,000-cycle life. Wetted materials include stainless steel, PEEK, PPS, and EPDM to ensure chemical resistance and fluid compatibility. The Lee Co., 2 Pettipaug Rd., Westbrook, CT 06498.
 

Diaphragm valve

A manual diaphragm valve is suitable for use in dialysis machines and abrasive media, vacuum, flow control, and cleanroom applications. The compact design of the Type 314 valve was made possible by casting the lower body with connection threads as one piece. The valve is available in polypropylene, PVDF, and PVC, and features end connections for bead- and crevice-free infrared socket and butt fusion. Other features include an optional locking handwheel, position indicator, and threaded mounting inserts. George Fischer Inc., 2882 Dow Ave., Tustin, CA 92780.

High-flow check valves

Clear one-way check valves offer unimpeded fluid flow, low opening pressure, and no backflow, even at low back pressures. The valves can handle a much greater flow rate than duckbill, ball-check, or disk-type valves. Made of medical-grade plastics and silicone, the valves can be EtO or gamma sterilized. Miniature valves with luer end and steam-autoclavable valves are available upon request. Resenex Corp., 9614-F Cozycroft Ave., Chatsworth, CA 91311.
 

Miniature check valves

A manufacturer offers a line of miniature check valves and fixed-flow controls. The metal ball-type check valves are available in brass or stainless steel and are suitable for use with liquids or gases. The fixed-flow controls, which consist of a ball check valve and a precision orifice arranged in parallel, are tamperproof and ensure unchanged operation. Free flow occurs in one direction, while metered flow occurs in the opposite direction. The valves and flow controls are manufactured with 10-32 threaded connections, 1/4- and 1/8-in. NPT threads, and press-in inserts. O'Keefe Controls Co., P.O. Box Q, Trumbull, CT 06611.
 

Vacuum valves

Bellow-sealed vacuum valves have a low leak rate and are constructed of a 304-stainless-steel body, making them resistant to particle damage. Angle and in-line valves can be operated manually, pneumatically, or electropneumatically. The 4-in. valves can be customized for the user with a choice of flanging, seals, solenoid voltages, and a limit switch option. MKS Instruments, 5330 Sterling Dr., Boulder, CO 80301.
 

Check valves

Modular plastic check valves can be used for gas analysis, filtration, and medical diagnostic and treatment equipment. The valves incorporate a low-inertia poppet design with double-tapered O-ring seals to achieve a fast seal in ultra-low-pressure applications. Available in a wide range of thermoplastic materials, the valves provide corrosion resistance, offer a choice of flow direction, and can operate in temperatures ranging from 0° to 250°F. Customers can specify end fittings, cracking pressure, O-rings, and body and spring materials. Smart Products Inc., 1710 Ringwood Ave., San Jose, CA 95131.
 

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