In refrigeration technology, semi-hermetic reciprocating refrigerant compressors are a central component of many refrigeration systems. Effective lubrication is essential to ensure the optimum performance and longevity of these compressors. A decisive factor here is monitoring the oil pressure, especially in pump-lubricated systems. This is where the electronic differential pressure sensors of the Delta-P product family come into play, ensuring reliable monitoring and thus protection of the compressors.
 

Functionality and design of the Delta-P differential pressure sensors
The Delta-P differential pressure sensors consist of two main components: a screw-in part (sensor) and an electronic evaluation unit. These two parts are physically separable, which facilitates replacement and maintenance. The sensor is screwed directly into the pump housing on the bearing cover of the compressor and is connected to the suction and high-pressure sides of the oil pump via channels. This allows the differential pressure to be measured precisely.
The direct screwing of the KRIWAN Delta-P oil differential pressure sensor into the pump housing of the compressor eliminates the need for additional, break-prone pipe connections, which further increases safety and reliability. An LED status indicator (optional) also enables the safety status to be recognised quickly and easily.
 

Monitoring the oil pressure
The differential pressure sensor continuously monitors the pressure difference between the suction and high-pressure sides of the oil pump. If this differential pressure is below the permissible value for an extended period of time, the system's safety chain is permanently interrupted to prevent damage. Even shorter periods of low oil pressure lead to the compressor being switched off after a correspondingly longer delay. This effectively prevents serious damage to sliding surfaces and bearing points that could be caused by insufficient lubrication.
 

Advantages of Delta-P differential pressure sensors
The Delta-P differential pressure sensors offer a number of advantages that make them a preferred choice for oil pressure monitoring:

• Easy installation and replacement: the sensor can be screwed directly into the pump housing, eliminating the need for additional pipe connections that are prone to breakage. This also makes it possible to remove or replace the sensor when the refrigeration circuit is closed.
• High reliability: With a low leakage rate and the ability to self-monitor device function, these sensors offer high reliability in operation.
• Visual status information: A visual status indicator allows easy monitoring and control of the system.
• Safety compliance: The devices are UL and CE compliant, ensuring their compliance with international safety and quality standards.
• Simple integration: The potential-free changeover contact enables simple integration into existing safety circuits.
   

Importance of oil pressure monitoring
Sufficient oil pressure is essential for the lubrication and protection of the internal components of a compressor. A failure of the oil feed pump or foaming chiller oil can lead to low oil pressure. Without effective monitoring, such problems could go undetected and cause serious damage. Therefore, differential pressure sensors such as the Delta-P series are essential components for the safe and efficient operation of reciprocating refrigeration compressors.

The Delta-P differential pressure sensors offer a reliable and effective solution for monitoring oil pressure in semi-hermetic reciprocating refrigerant compressors. Thanks to their simple installation, high reliability and numerous advantages, they contribute significantly to the safety and longevity of refrigeration systems. The implementation of such monitoring systems is therefore not only a recommended but also a necessary measure for the operation of modern refrigeration systems.

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