KVC & KVL Valves – The Key Components for Maintaining a Stable Pressure Dew Point in Refrigerated Air Dryers
In a refrigerated compressed air dryer, maintaining a stable Pressure Dew Point (PDP) is critical to ensuring high-quality compressed air, preventing moisture condensation within the piping system, and protecting downstream pneumatic equipment.
To achieve this, two essential refrigeration control valves are widely used:
- KVC Hot Gas Bypass Regulator
- KVL Crankcase Pressure Regulator
These pressure-regulating valves play a vital role in maintaining refrigeration system stability, protecting the compressor, and ensuring the refrigerated air dryer consistently delivers a pressure dew point between 3°C and 7°C, which is the industry standard for most industrial compressed air systems.
What is a KVC Hot Gas Bypass Regulator?
The KVC Hot Gas Bypass Regulator is a pressure-regulating valve designed to bypass a controlled amount of hot refrigerant gas from the compressor discharge line back to the suction line whenever the refrigeration load decreases.
Main Functions of the KVC Valve
- Maintains stable compressor suction pressure.
- Prevents evaporator icing during low-load conditions.
- Keeps the pressure dew point stable at approximately 3–7°C.
- Ensures smooth operation when compressed air demand fluctuates.
- Reduces excessive compressor cycling.
- Extends the service life of the refrigeration compressor and related components.
Problems Caused by a Faulty KVC Valve
A malfunctioning KVC valve may result in:
- Unstable pressure dew point.
- Evaporator coil icing.
- Excessively low suction pressure.
- Unstable refrigeration compressor operation.
- Reduced compressed air quality.
- Increased maintenance costs and unexpected downtime.
What is a KVL Crankcase Pressure Regulator?
The KVL Crankcase Pressure Regulator is installed in the compressor suction line to limit the maximum suction pressure entering the refrigeration compressor.
Its primary purpose is to protect the compressor from excessive load, particularly during startup or after defrost cycles.
Main Functions of the KVL Valve
- Protects the refrigeration compressor during startup.
- Limits excessive suction pressure.
- Reduces compressor starting current.
- Prevents motor overload.
- Extends compressor service life.
- Suitable for refrigeration systems using R22, R134a, R404A, and R407C refrigerants.
Why Are KVC and KVL Valves So Important in Refrigerated Air Dryers?
In industrial compressed air systems, air consumption continuously varies depending on production demand.
When compressed air demand decreases:
- The refrigeration load decreases.
- Suction pressure drops rapidly.
- Evaporating temperature falls.
- The evaporator is more likely to freeze.
At this point, the KVC valve automatically bypasses hot refrigerant gas to maintain a stable evaporating pressure and prevent icing.
Meanwhile, the KVL valve limits the maximum suction pressure acting on the refrigeration compressor, protecting it from overload during startup and transient operating conditions.
Together, these two valves are considered critical components that determine the stability, efficiency, and reliability of a refrigerated compressed air dryer.
Technical Specifications – KVL Crankcase Pressure Regulator
| Model |
R22 Capacity (Ton) |
R134a (Ton) |
R404A (Ton) |
R407C (Ton) |
Solder ODF Connection |
| KVL12 |
1.2 |
0.8 |
1.0 |
1.1 |
1/2" |
| KVL15 |
1.2 |
0.8 |
1.0 |
1.1 |
5/8" |
| KVL22 |
1.2 |
0.8 |
1.0 |
1.1 |
7/8" |
| KVL28 |
4.1 |
2.6 |
3.4 |
3.8 |
1-1/8" |
| KVL35 |
4.1 |
2.6 |
3.4 |
3.8 |
1-3/8" |
General Specifications
- Pressure Setting Range: 3–87 psig
- Maximum Working Pressure: 261 psig
- Maximum P-band:
- KVL12 / KVL15 / KVL22: 29 psi
- KVL28 / KVL35: 22 psi
- Refrigerant Temperature Range: -75°F to 266°F
KVL Dimensions
| Model |
ODF (mm) |
H1 (mm) |
H2 (mm) |
B1 (mm) |
C (mm) |
ØD (mm) |
| KVL12 |
12 |
179 |
99 |
64 |
10 |
30 |
| KVL15 |
16 |
179 |
99 |
64 |
12 |
30 |
| KVL22 |
22 |
179 |
99 |
64 |
17 |
30 |
| KVL28 |
28 |
259 |
151 |
105 |
20 |
43 |
| KVL35 |
35 |
259 |
151 |
105 |
25 |
43 |
Technical Specifications – KVC Hot Gas Bypass Regulator
| Model |
R22 Capacity (Ton) |
R134a (Ton) |
R404A (Ton) |
R407C (Ton) |
Solder ODF Connection |
| KVC12 |
7.6 |
4.8 |
36.9 |
8.4 |
1/2" |
| KVC15 |
14.9 |
9.4 |
13.6 |
16.4 |
5/8" |
| KVC22 |
19.1 |
12.0 |
17.4 |
21.0 |
7/8" |
General Specifications
- Pressure Setting Range: 3–87 psig
- Maximum Working Pressure: 406 psig
- Maximum P-band: 29 psi
- Refrigerant Temperature Range: -75°F to 266°F
KVC Dimensions
| Model |
ODF (mm) |
NV1 |
NV2 |
H1 (mm) |
H2 (mm) |
B1 (mm) |
C (mm) |
ØD (mm) |
| KVC12 |
12 |
19 |
19 |
179 |
99 |
64 |
10 |
30 |
| KVC15 |
16 |
24 |
24 |
179 |
99 |
64 |
12 |
30 |
| KVC22 |
22 |
— |
— |
179 |
99 |
64 |
17 |
30 |
The Ideal Solution for Stable Dew Point Control
Selecting the correct KVC Hot Gas Bypass Regulator and KVL Crankcase Pressure Regulator is essential for maintaining the long-term reliability and performance of refrigerated compressed air dryers.
These valves help to:
- Maintain a stable 3–7°C pressure dew point.
- Prevent evaporator freeze-up.
- Protect the refrigeration compressor from overload.
- Improve overall refrigeration system efficiency.
- Reduce maintenance costs and equipment downtime.
- Deliver clean, dry, and reliable compressed air for industrial applications.
Whether used in OEM refrigerated air dryers or replacement maintenance projects, KVC and KVL pressure regulators are indispensable components for ensuring consistent refrigeration performance and maximizing system lifespan.
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