Spotlight on Pumps and Valves
Isolation valves
Inert solenoid-operated isolation valves can accommodate a significant level of precipitates, particles, and contamination. The valves are supplied in 1/16-, 3/32-, 1/8-, and 1/4-in. barbed ports, 10-32 and 1/4 X 28 threaded ports, and two manifold configurations. Miniature sizes feature maximum 1/8-in. ports, -12 to 35 psi pressure capability, and flow rates of 800 ml/min at 15 psid (liquid) or 40 L/min at 35 psid (air). Standard sizes with ports up to 1/4 in. are also offered. Available in 12- and 24-V-dc versions, the valves have a life-span attaining 300 million cycles. Applications range from various blood-cell analysis functions to clinical chemistry equipment. The company also manufactures products designed for flow control of medical and respiratory gases. South Bend Controls Inc., South Bend, IN, USA.
Diverting valve
A three-way sanitary diverting valve that is completely free-draining is available in manually or pneumatically operated versions. The pneumatic model functions in normally open or normally closed mode; it can also be operated with an adjustable-flow push-button actuator. Available in sizes ranging from 12 to 51 mm and in a choice of standard diaphragm materials, the valve can withstand pressures up to 10 bar G and is steam sterilizable. The AISI 316L can be fitted with position sensors for more advanced automation requirements. NovAseptic Equipment AB, Nodinge, Sweden.
Pinch valves
Pinch valves can perform 2.5 million operations without experiencing a loss in productivity. The dual-tube valves, which can be used in single-tube configurations, are compatible with rubber and Tygon tubing and have been designed to work with thicker tubes than previous models. They have a pressure capability of 1.5 bar and operate at either 12 or 24 V dc. The PM-1015W is specified for 1 X 3 mm tubing; the PM-0815W is suited for 0.8 X 2.4-mm tubing. The valves remain continuously energized over long periods. Mindsmeet, St. Neots, Cambs, UK.
Check valves
Plastic check valves supplied in a variety of styles and materials, and with cracking pressures that range from 3 in. of water to 17 psi, allow more than 16,000 configurations. The cartridge design enables insertion of the check valve into tubing, manifolds, and virtually any mounting. Customer-specified custom configurations--from the end fittings to the spring material--can be realized using stock parts, thereby eliminating the need for costly special components. The check valves feature a low-inertia poppet and double tapered O-ring seats, and exhibit negligible pressure drop and full flow in the open position. The West Group Ltd., Portsmouth, Hants, UK.
Vacuum pumps
Compact compressed airdriven vacuum pumps operate according to the multistage Venturi principle. Suitable for filtration, rotary evaporation, centrifuging, and related applications, the pumps attain vacuum levels down to 15 mbar and flow rates of 30 to 170 L, depending on the model. The pumps are designed for optimum chemical resistance to various solvents and acids. Because they are compact and lightweight, the Lab Vac series features easy installation in fume cabinets and similar locations close to where the vacuum pump will be used. An energy-saving pressure switch is available as an option. Piab AB, Täby, Sweden.
Needle valves
Needle valves offer precise flow control for instrumentation and industrial applications. The flow, which is restricted in both directions, can be adjusted from 0 to the equivalent flow of a 0.25-in. orifice. Two models are available--a glass-filled nylon valve with straight ports or barbs and a polypropylene version with straight ports for applications where chemical resistance is a concern. Both types of needle valves are suited for in-line installation or panel mounting and come with a choice of nickel-plated brass or stainless-steel handles. Needle valves are available with a screwdriver slot-adjustment or knurled knob, and Buna-N, Viton, or ethylene-propylene O-rings. Air Logic, Racine, WI, USA.
Mini-diaphragm vacuum pumps
Vacuum pumps deliver flow rates up to 34 L/min despite their small size, the result of a patented diaphragm design. The mini-diaphragm pumps in the N 815 and N 828/838 range are suited for the clean evacuation and delivery of air and gases in medical equipment. Because they operate without oil, the pumps will not contaminate or falsify the media they handle. The components are designed for maintenance-free operation and exhibit a high degree of vapour tolerance. KNF Neuberger, Freiburg, Germany.
Peristaltic pump
A perstaltic pump's head features a single roller/rotor that is eccentrically attached to the cam. In its highest position, the roller/rotor simultaneously opens a static inlet and outlet valve while pushing the fluid forward. This new pump design permits dosing applications down to microlitre/min while maintaining high precision and low pulse rates. The proprietary system can be adjusted to handle nearly any volume. The pump is suited for medical dosing devices and scientific analysis intrumentation. KBL GmbH, Karlstein, Germany.
