Application Spotlight: Biomedical Flow Monitoring

Dialysis Cmt Blog

Hospitals employ sophisticated equipment incorporating complex fluid handling and monitoring systems. This is because liquids and gases are used extensively to prepare devices and instruments for use, for cooling, heating, and for taking on essential bodily functions. Whenever fluids are pumped and filtered there’s a risk of leaks and blockage. Either will cause abnormal flows, and in the biomedical sector such failures can have serious consequences. Here’s an overview of four places where it’s important to know correct flow rates are being maintained.

Steam sterilization/autoclave systems

In medical environments various degrees of sterilization are used to prevent transmission of infection. Naturally enough, anything going into the human body, such as medical devices or surgical instruments, needs the very highest levels of cleanliness. The most widely used method of achieving this is by autoclave.

An autoclave uses steam to destroy contamination. However, as endospores, protozoean cysts, and some viruses can survive temperatures of 100 C pressurization raises the steam temperature to 121 C or higher. Hospitals sometimes connect autoclaves into a central steam system but many are standalone units generating their own steam from a water reservoir. These pump water into a pressure vessel, creating, venting, and condensing steam as necessary. Any deviation from correct operating conditions could result in not achieving adequate sterilization conditions.

CT scanner cooling

CT equipment uses x-rays to image the inside of the human body. Generating x-rays takes a lot of electrical power, and heat is an inevitable byproduct. A cooling system forms an integral part of every CT scanner, using water, (sometimes air) to keep temperatures within safe operating limits. In a water cooled system pumps move chilled water through the machine and from there to a heat exchanger. Should water flow drop below required levels the machine could potentially overheat.


The ventilator delivers air into the lungs of someone having difficulty breathing. Most are considered “positive pressure ventilators” because they move an oxygen-air mixture in, but let the patient breathe out. Typically, a ventilator has an oxygen-air mixing unit combined with a pumping system comprised of pistons, bellows or pneumatic circuits. Any deviation in the mix proportions from target levels could have serious consequences, so it’s important to be sure gases are flowing at the correct rates at all times.

Dialysis machines

A dialysis machine, used by people suffering kidney failure, filters and balances the electrolytes, pH, and fluid concentration in blood. Dialysis machines can be large clinical units or smaller home-use equipment. They consist mainly of pumps, filters, monitors, and alarms that mix and deliver the “dialysate.” This is the mixture of water, bicarbonate and acid solutions needed by the patient.

The dialysate circuit brings in water, heating and degassing it before mixing with the bicarbonate and acid solutions. Maintaining correct flows is essential for accurate proportioning and any blockage or leak would be a problem.

Importance of flow monitoring

IMG_9949-e1433168120931-300x400These examples illustrate some of the many applications where flow monitoring can help improve equipment reliability and performance. ChemTec manufactures a range of flow monitors at their factory in Deerfield Beach, Florida, including the non-adjustable LPH series.

Intended for low-flow applications, LPH flow monitors detect both high and low flow conditions and have a close on-off differential for high sensitivity. Designed without seals, they perform reliably with both corrosive and non-corrosive liquids and gases.

Contact Chemtec at 800-222-2177 to discuss your unique application.