Pressure transmitters are widely used in refrigeration systems across many industries, including food and beverage, healthcare, and chemical processing. While refrigeration systems might seem straightforward, selecting a suitable pressure transmitter is critical for ensuring system reliability and longevity. This guide highlights key factors to consider when choosing a pressure transmitter for refrigeration applications.

Applications of Refrigeration Systems

Refrigeration systems are essential in various fields:

• Food and Beverage: Advanced refrigeration is used for more than just food cooling. These systems are crucial in food processing and storage.
• Healthcare: Blood banks and laboratories rely on refrigeration for preserving biological and pharmaceutical materials. During blood transfer, ambulances must have refrigeration equipment on their vehicles for medication stored onboard and the refrigeration system must remain running while the vehicle is idle at the station.
• Chemical Processing: Large-scale refrigeration systems are integral to many industrial processes.

Pressure Transmitter Specifications for Refrigeration

Pressure transmitters for refrigeration typically need to meet several industry norms:

• Pressure Ranges: Generally, low-pressure systems are used in refrigeration, with pressures around 75 psi on the evaporation side and up to 300 psi on the condensing side.
• Process Connections: Common standards include National Pipe Thread (NPT) in the U.S. and G1/4 connections internationally. In the U.S., 7/16-20 Schrader connections are also widely used.
• Temperature Tolerance: Transmitters should withstand temperatures from -40 to 125°C to handle ambient and colder media temperatures.
• Output Signals: Systems often use output signals such as 4-20 mA or 0.5-4.5 Vdc, depending on the control system.
• Environmental Protection (IP Ratings): Dust protection (IP6x) is typical, with additional water protection ratings (IPx5 to IPx8) to guard against water ingress from frost.

Special Considerations for Refrigeration Applications

Two additional factors can help extend the life and accuracy of pressure transmitters in refrigeration applications:

1. Low-Temperature Fill Fluid:
   • Many low-pressure transmitters use piezoresistive pressure sensors with silicone oil as a fill fluid. Standard silicone oil can become too thick at low temperatures, slowing the sensor’s response time and reducing accuracy.
   • For applications requiring quick response and high accuracy, consider a low-temperature fill fluid, though it may increase costs and lead times.
2. Moisture Ingress and Humid Air:
   • Most low-pressure transmitters include a backside vent (P2 vent) for accurate gauge pressure measurements. However, this vent can let humid air into the device, which may condense at cold temperatures and damage electronics.
   • A sealed gauge transmitter or a fully potted enclosure (encased in protective material) can help prevent moisture ingress, improving the device’s durability and reducing the risk of failure.

Selecting the right pressure transmitter for refrigeration systems is essential to meet specific application needs and ensure reliable performance. NOSHOK PT30 pressure transmitters are a versatile choice, designed to meet the demands of various refrigeration applications and provide long-lasting performance.