Component Operation and Maintenance, Checks and Adjustments

Adjustment

To adjust the superheat setting, proceed as follows:

1.Remove the valve cap at the bottom of the valve.

2.Turn the adjusting stem counterclockwise to lower the superheat.

3.Turn the adjusting stem clockwise to increase the superheat.

NOTE

Make no more than one turn of the stem at a time. As long as thirty minutes may be required for the new balance to take place.

7.4.6Hot Gas Bypass Valve

Operation

The hot gas bypass is inserted between the compressor discharge line and the leaving side of the expansion valve through the side outlet distributor (refer to Figure 7). The system, during normal operation, when the evaporator is under full load, will maintain enough pressure on the leaving side of the hot gas valve to keep the valve port closed.

If the load on the evaporator decreases, the evaporator will get colder. When the coil is too cold, the internal pressure in the evaporator drops and allows the hot gas bypass valve to open. Hot gas then mixes with the liquid coolant on the discharge side of the expansion valve, raising the temperature and pressure in the evaporator. The net result is a reduction in the cooling capacity of the unit to match the load.

Adjustment

Upon deciding what evaporator temperature is desired, the following procedure should be used to adjust the hot gas bypass valve:

1.Install the suction and discharge pressure gauge.

2.Turn thermostat to call for cooling so that the refrigeration compressor will run.

3.Remove the TOP adjusting nut from the valve.

4.Insert an Allen wrench in the brass hole at top of valve in adjusting port, and turn CLOCKWISE if a higher evaporator temperature is required.

5.After obtaining the suction pressure required, reinstall cap tightly making sure there are no leaks.

6.Let the evaporator operate for approximately 10 to 15 minutes to make sure the suction pressure is within the range desired.

7.There will be a fluctuation of approximately 3 to 6 PSIG (21 to 41 kPa) on the evaporator due to the differential on the hot gas bypass.

Figure 7 Hot gas bypass

External Equalizer

Evaporator

External

Equalizer

Hot Gas

Solenoid Valve

Compressor

Solenoid Valve

TEV

Side Distribution

Connector or ASC

Discharge

Bypass Valve

Condenser

53

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Emerson DE, VH, VE, DH manual Adjustment, Hot Gas Bypass Valve Operation
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VE, DH, VH, DE specifications

Emerson is a well-known brand in the field of automation solutions, offering a range of products that cater to various industries. Among its diverse portfolio, Emerson’s products like DE (Digital Electronics), VH (Variable Frequency Drives), DH (Distributed Control Systems), and VE (Valve Positioners) stand out for their advanced features, cutting-edge technologies, and unique characteristics.

Digital Electronics (DE) from Emerson represents the backbone of modern automation systems. These devices are characterized by their highly reliable digital communication capabilities, providing robust solutions for process monitoring and control. DE products integrate seamlessly with various automation platforms, allowing for easy data exchange and system interoperability. The advanced analytics embedded in these systems enable predictive maintenance strategies, enhancing overall operational efficiency.

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In summary, Emerson's DE, VH, DH, and VE offerings embody the latest innovations in automation technology. Their main features, including digital communication, energy efficiency, scalability, and precision control, cater to the diverse demands of modern industries. With these products, Emerson not only enhances operational efficiency but also paves the way for intelligent automation solutions that are crucial for the future of industrial processes.
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