A Pressure Transducer that Can Handle Just About Anything

Author: Wika

Have you ever had a pressure transducer succumb to high pressure, extreme heat, or cold? Have you had an application fail because a pressure transducer did not live up to its expectation? WIKA offers the R-1 as the latest generation of pressure transducers using thin-film and thick-film ceramic technologies for refrigeration and air conditioning systems.

The R-1 pressure transducer is tested using strict protocols designed specifically for the refrigeration and HVAC industry. It meets or exceeds all test requirements including resistance to icing, heating, high pressure steam jets, internal condensation, submersion, and dust tightness.

 

Image Captions (Left to Right)

• Heat cycling: -15°F to +140°F to EN 60068-2-38
• Dust resistance: Ingress Protection IP6X according to EN 60529
• Submersion: 15PSI at 75°F for 30 minutes
• Freeze / thaw cycling: 40°F to 23°F for 240 hours

 

Image Captions (Left to Right)

• High pressure steam washdown: Ingress Protection IPX9K to DIN 40050-9
• Condensation: +115°F ambient at 85% RH, media temp 15°F for 500 hours

Long-Term Integrity
Long-term leak resistance of the R-1 pressure transducer is achieved through the hermetically sealed, welded thin-film sensor and process connection. Elimination of soft sealing materials removes the need for additional material compatibility testing and eliminates the chance of long term leaks developing due to seal deterioration.

Refrigeration & AC System Overview
With the rapid increase in energy costs, energy efficient refrigeration and HVAC systems are essential. If operating your plant’s refrigeration systems involves a significant electricity expense, WIKA presure transducers for refrigeration and air conditioning can significantly reduce energy consumption when used in conjunction with a PLC based control system. Permanently installed pressure transducers make it simple to monitor the performance of your system and identify any problems that may occur.

The photograph at right is an example of a refrigeration application for which the WIKA R-1 pressure transducer would be used.

Description of a typical refrigeration cycle

Step 1: Beginning at the compressor, the refrigerant is compressed and leaves the compressor as a high temperature, high pressure gas.

Step 2: The hot refrigerant enters the condenser, which is usually fan forced air cooled; then the refrigerant leaves the condenser as a warm liquid and continues on to the thermal expansion valve.

Step 3: The expansion valve meters the proper amount of refrigerant into the evaporator.

Step 4: The sudden pressure drop after the expansion valve converts the high pressure warm liquid refrigerant into a low pressure, cold gas. The cold gas absorbs ambient heat from fan forced air passing through the evaporator. This ambient heat converts the refrigerant into a cool dry gas. From here the refrigerant reenters the compressor to be pressurized again and the cycle repeats.

The diagram below shows a typical refrigeration cycle. Image modified from Natural Resources Canada

Pressure transducers are used on both the high pressure side and low pressure side of the compressor to control and optimize the cycle.

Low refrigerant charge in a refrigeration system is detected by monitoring the compressor’s discharge of pressure and temperature. This monitoring is accomplished with a WIKA pressure transducer located at or near the compressor outlet. Output signals from the pressure transducer are sent to a PLC. When a high discharge temperature with a low discharge pressure is detected, the PLC provides a low charge signal. The PLC can also receive input about additional operating characteristics of the refrigeration system to provide a more accurate low charge signal. The PLC is connected to a warning indicator and compressor so that the low charge signal activates the indicator and deactivates the compressor.

Refrigeration systems often suffer from hidden equipment faults and inefficient controls. Undetected problems in a refrigeration system can result in high energy costs and shorten the life of the equipment. By installing the proper monitoring equipment and adopting an efficient control strategy, costly problems can be prevented.

Potential problems

• Suction line filters keep the refrigerant clean and protect the compressor from taking in debris. If one of the filters becomes clogged, the restricted flow will create a pressure drop in the system. This drop will reduce efficiency and lead to unnecessary costs.
• Hidden refrigerant leaks can eventually lead to a low refrigerant charge. Repairing leaks can bring about a remarkable performance boost. A low charge can cause efficiency losses and add to annual operating costs.
• In many refrigeration systems, head pressure stays at a fixed level to assure reliability over numerous temperature ranges. This also assists in maintaining sufficient refrigerant flow, freeze protection for the condenser and an adequate pressure difference across expansion valves.

The WIKA R-1 pressure transducer is produced on a modern, highly flexible production line which meets the highest quality standards. With the R-1 pressure transducer, WIKA offers absolute reliability at a low cost, without compromising quality, safety or affordability.

If you would like more information about the Wika R-1 Pressure Transducer or any other Wika Products please contact Forberg Scientific, Inc. Customer Service.
Toll Free: 855-288-5330
Email: mechanicalsales@forberg.com