Expansion Valve

1. Mounting:

For mounting of Expansion devices in the refrigeration circuit is varied based on different types. For capillary tube is a minimum diameter hose which is mounted between condenser and evaporator coil. For Thermostatic expansion valve which is fixed horizontally and the sense bulb is fixed at the evaporator outlet. For Electronic expansion valve is controlled by using controller to maintain different super-heat. It is fixed horizontally with the sense bulb is located at the outlet of the evaporator with proper insulation.

2. Application Range:

Capillary tube is used in low load applications such as freezers, water cooler etc. Typical tube diameters of refrigerant capillary tubes range from 0.5 mm to 3 mm and the length ranges from 1.0 m to 6 m. Thermostatic expansion valve is the most versatile expansion valve is used in medium and high load applications and is most commonly used in refrigeration systems. A thermostatic expansion valve maintains a constant degree of super-heat at the exit of evaporator.

Electronic expansion valve is used in medium and high load applications. It is convenient to use it in air-conditioning systems, which serve as heat pumps in winter with reverse flow.

3. Installation procedure:

· Select the correct size of capillary tube based on the applications

· Capillary tube is perfectly brazed into the pipeline.

· Pressurize and leak test the entire system including the Condensing Unit, Evaporator and all connected tubing, fitting and brazed joints properly using the nitrogen for leak testing.

· The Unit must be securely installed on a stable and rigid support, and fix from the beginning.

· Avoid material entering into the system while cutting tubes. Never drill holes where burrs cannot be removed.

· For thermostatic expansion valve, which is installed perfectly with brazing

· The sense bulb is placed at the exit of evaporator coil with proper insulation

· For electronic expansion valve is fixed as per the procedure of TXV and the controller is placed rigidly without any damage.

4. Piping connections:

In order to make the connections, liquid line piping with the correct diameters is provided for proper refrigerant flow rate and pressure should be reduced as per design conditions.

5. Electrical connections:

· Ensure that power supply cannot be switched on during installation.

· All electrical components must be selected as per local standards and unit requirements.

· Refer to wiring diagram of electronic expansion valve for electrical connections details and there is no wiring connection for capillary tube and TXV.

· Ensure that the power supply corresponds to the unit characteristics and that the power supply is stable.

· Dimension the power supply cables according to unit data for voltage and current.

· Protect the power supply and ensure correct earthing.

6. Check list during Startup:

· Check the expansion device is fixed properly.

· Check the insulation of sense bulb and position of sense bulb properly.

· Check power supply of Electronic Expansion valve with controller.

· Never start the Unit when no refrigerant is charged.

· All service valves must be in the open position.

· Check the leakage in the pipeline between condenser and evaporator.

7. Check list with running unit:

· Check the functions of electronic controller.

· Check the pressure drop of expansion devices.

· Check the sense bulb reading correctly.

· Check all abnormal vibration of the unit.

· Check the leakage of pipeline in the expansion device.

8. Maintenance

· Maintain the sense bulb insulation periodically.

· Clean the electronic controller properly.

· When machine parts need replacing, use manufacturer’s original parts only.

· Check that all electric terminals, both on electrical panels and terminal boards are properly connected and also check carefully that all fuse elements are correctly clamped.

· Check for ticking or vibrations that result from breakdowns or excessive mechanical friction between moving parts.

· Maintain periodic maintenance report regularly.

· Ensure piping connections of expansion device has no failure.

9. Service

· If sense bulb is not working properly, replace another one.

· For damage of electronic controller wiring happen, replace as per standard.

· If electronic controller not functioning correctly replace it.

· If any leakage happens in the pipeline, just find the leakage area and braze it properly or replace full pipeline setup.

· If damage of expansion device happens replace it as per standard condition.

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