Pressure Switches for Alarm Systems.

Pressure switches are often used as part of an alarm system to safeguard continuous operation. This is common in a variety of industries and we have come across many in medical applications.

This type of pressure measurement in medical devices can be critical to the patient. The job of the pressure switch is to give an indication of when a system is running outside of its safe parameters, either too low or too high.

Medical Gas Systems in Hospitals

Pressure switches are used in this way in oxygen tanks in hospitals. When a patient needs oxygen, it is important for the doctors and nurses to be able to provide a mask with a guaranteed supply. As you can imagine, providing a patient with a mask that has no oxygen flowing would be very problematic. So on the air delivery system, a pressure switch is mounted to monitor the oxygen level within the tank. The pressure inside the tank is monitored by the pressure switch. When the amount of oxygen drops below a certain level the switch will raise the alarm and the tank can then be refilled before use.

Patient Safety on Medical Equipment.

You may have read our press release about the Physiolab Thermal Compression Unit. This unit uses pressure switches in an alarm system to prevent the crushing of limbs. The Physiolab machine uses an anatomical therapy pack which goes over the leg or arm of the patient and fills with hot and cold fluid. The anatomical therapy pack contains a pressure switch on the system to help ensure the pack doesn’t fill with too much fluid and crush the limb of the patient.

Pressure switches for DNA Sampling

Pressure switches are also used as part of the alarm system on a DNA sampling machine. Here, the pressure switch will make sure the solution is running through the machine ready to collect the DNA sample. This gives a sterile DNA sample and often can collect more information than a standard swab. Without the fluid being there the sample could be spoiled and ruin potential evidence.

Static or Gauge Pressure

When pressure switches are used in alarm systems they use Static or Gauge Pressure, this is the most common type of pressure reference.

Gauge pressure switches have just one port and the system pressure is directed through to the sensing diaphragm. Changes in the system pressure deform the diaphragm, this will trigger the pressure switch to activate on or off accordingly.

The diagram below shows a drawing of how the PSF103 pressure switch works in this way.

If you would like more information on pressure switches for alarm systems or pressure switches in general please contact us 01327 351004 orsales@variohm.com