Spotlight on Flow-Control Components

Miniature full-ceramic bearings
An extended line of full-ceramic bearings is suitable for medical device flow-control applications. Balls made from ceramic silicon nitride exhibit greater hardness than steel balls, according to the manufacturer. They also have smoother surface properties than steel balls, resulting in less friction between the balls and bearing-race surfaces. While electromagnetic forces can cause frosting or fluting in the inner and outer races of antifriction chrome-steel bearings, ceramic hybrid bearings eliminate scarring and also run cooler because of reduced microweld adhesion. Available in sizes down to 3 mm, as well as in flanged sizes, the lightweight LBT Mini bearings operate at high speeds in harsh environments in which high temperatures and corrosive substances are present.
Boca Bearing
Delray Beach, FL
www.bocabearings.com

Insertion-style electromagnetic flow sensor
Used for batching, measuring incoming water, and monitoring chemicals or waste effluents in a variety of medical applications, an insertion-style electromagnetic flow sensor features built-in display, empty pipe detection, and bidirectional flow capabilities. Available with PVDF and Hastelloy C wetted parts, the 2551 Magmeter does not have moving parts to wear or foul. In addition, the all-in-one device allows local measurement readings, reducing the number of separate components required at the sensing point. Its display indicates flow rate, permanent flow total, and resettable flow total in a 2 × 16-character dot-matrix LCD format. For further flexibility, the unit can be ordered with optional mechanical single-pole, double-throw, or solid-state relays for alarm indication or control of valves or pumps. Its frequency output is bidirectional, while the 4- to 20-mA output can be set for single or bidirectional flow.
GF Piping Systems
Tustin, CA
www.gfpiping.com

Elastomeric flow-control valve
Developed to ensure dimensional accuracy and close tolerances in medical applications requiring effective bidirectional or one-way flow control, an elastomeric flow-control valve features medical-grade silicones and elastomers. Suitable for use in wound-management, respiratory-therapy, drug-delivery, IV-therapy, and other medical applications, the MediFlo valve can withstand EtO, E-beam, gamma, and autoclave sterilization processes. The valve is designed to replace normally open duckbill valves, which provide low flow rates and poor checking and cutoff capabilities in low-pressure applications, according to the manufacturer. Normally closed, this flow-control valve opens only when a desired pressure is reached. Featuring a rolling sleeve and head, it treats opening pressure, closing pressure, and flow rate as independent variables, enabling the design of custom models.
Liquid Molding Systems Inc.
Midland, MI
www.siliconelms.com

Miniature liquid diaphragm pumps
Available in a compact envelope and featuring an operating lifetime of more than 10,000 hours, miniature liquid diaphragm pumps are based on brushless motor technology. The Hargraves LTC-series miniature diaphragm pumps have Fluid-Blok sealing technology and a monolithic diaphragm design, which can eliminate leaks and allow for maximum suction and priming even under dry conditions. An advanced flow path and efficient valve system maximize flow while consuming low amounts of power as well. Suitable for use in medical applications, the pump can be made from a range of wetted materials, including Teflon, Viton, EPDM, perfluoroelastomers, and chemically inert LCP.
Parker Precision Fluidics Div.
Hollis, NH
www.parker.com

Rotary valves
Rotary valves can be used either in flow-control applications or on syringe pumps. Manufactured in a proprietary manufacturing process using such standard polymers as PCTFE, PTFE, PEEK, and UHMWPE, the rotary valves do not seize up when exposed to crystallizing reagents. In addition, when they are coupled with the company's PTFE or UHMWPE seal technology, the valves provide zero dead volume, which provides accuracy, precision, and longevity.
TriContinent
Grass Valley, CA
www.tricontinent.com