Fitters notes Pressure regulators
Contents Page
Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
KVP evaporating pressure regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
KVR condensing pressure regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
KVL crankcase pressure regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
KVC capacity regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
KVD receiver pressure regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Identication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Soldering/brazing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Pressure testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Evacuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
KVP evaporating pressure regulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
KVL crankcase pressure regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
KVR + NRD condensing pressure regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
KVR + KVD condensing pressure regulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Danfoss pressure regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
regulators
Pressure
© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 35
Notes
36 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006
Fitters notes Pressure regulators
Application
KVP evaporating
pressure regulator
Type KV pressure regulators will control the low
and high pressure sides of the system under
varying load conditions:
KVP is used as an evaporating pressure
regulator.
KVR is used as a condensing pressure regulator.
KVL is used as a crankcase pressure regulator.
KVC is used as a capacity regulator.
NRD is used as a dierential pressure regulator
and as a receiver pressure regulator.
KVD is used as a receiver pressure regulator.
CPCE is used as a capacity regulator.
The evaporating pressure regulator is installed in
the suction line after the evaporator to regulate
the evaporating pressure in refrigeration systems with one or more evaporators and one
compressor.
In such refrigeration systems (operating on
dierent evaporating pressures) KVP is installed
after the evaporator with the highest evaporating
pressure.
Each evaporator is activated by a solenoid valve
in the liquid line. The compressor is contolled by
a pressure switch in a pump down function.
The maximum pressure on the suction side
corresponds to the lowest room temperature.
Ak0_0031
Ak0_0025
regulators
Pressure
In refrigeration systems with parallel coupled
evaporators and common compressors, and
where the same evaporating pressure is required,
KVP must be installed in the common suction
line.
The KVP evaporating pressure regulator has a
pressure gauge connection for use when setting
the evaporating pressure. KVP maintains constant
pressure in the evaporator.
KVP opens on rising inlet pressure (evaporating
pressure).
Ak0_0019
Ak0_0023
© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 37
Fitters notes Pressure regulators
KVR condensing
pressure regulator
KVR is normally installed between the air-cooled
condenser and the receiver. KVR maintains
constant pressure in air-cooled condensers.
It opens on rising inlet pressure (condensing
pressure).
KVR together with a KVD or an NRD ensures a
suciently high liquid pressure in the receiver
during varying operating conditions.
The KVR condensing pressure regulator has a
pressure gauge connection for use when setting
the condensing pressure.
Ak0_0026
In situations where both the air-cooled condenser and the receiver are located outdoors in
very cold surroundings it can be dicult to start
the refrigeration system after a long standstill
period.
In such conditions, KVR is installed ahead of the
air-cooled condenser, with an NRD in a bypass
line around the condenser.
NRV prevent back ow during start up process.
Ak0_0027
KVR is also used in heat recovery. In this
application, KVR is installed between the heat
recovery vessel and condenser.
It is necessary to install an NRV between condenser and receiver in order to prevent backcondensation of the liquid in the condenser.
Ak0_0028
KVR can be used as a relief valve in refrigeration
systems with automatic defrosting. Here, KVR
is installed between the outlet tube from
evaporator and receiver.
Note!
KVR must never be used as a safety valve.
Ak0_0029
KVL crankcase
pressure regulator
KVL crankcase pressure regulator limits compressor operation and start-up if the suction
pressure becomes too high.
It is installed in the refrigeration system suction
line immediately ahead of the compressor.
KVL is often used in refrigeration systems with
hermetic or semihermetic compressors designed
for low-temperature ranges.
KVL opens on falling outlet pressure (suction
pressure).
Ak0_0024
38 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006
Fitters notes Pressure regulators
KVC capacity regulator
KVC is used for capacity regulation in refrigeration systems where low-load situations occur
and where it is necessary to avoid low suction
pressure and “compressor cycling”.
Too low a suction pressure will also cause
vacuum in the refrigeration system and thus
create the risk of moisture ingress in refrigeration
systems with open compressor. KVC is normally
installed in a bypass line between compressor
discharge tube and suction tube. KVC opens on
falling outlet pressure (suction pressure).
Ak0_0030
A CPCE capacity regulator can be used as
an alternative to KVC if the requirement
is greater accuracy in the regulation, low
suction pressure or if higher pressure drop is
given between CPCE outlet and the suction
pressure.
KVD receiver
pressure regulator
KVC can also be installed in a bypass line from
the compressor discharge pipe, with valve outlet
led to a point between expansion valve and
evaporator.
This arrangement can be used on a liquid cooler
with several parallelcoupled compressors and
where no liquid distributor is used.
KVD is used to maintain suciently high
receiver pressure in refrigeration systems with
or without heat recovery.
KVD is used together with a KVR condensing
pressure regulator.
The KVD receiver pressure regulator has a
pressure gauge connection for use when
setting receiver pressure.
KVD opens on falling outlet pressure (receiver
pressure).
Ak0_0002
Ak0_0003
regulators
Pressure
Ak0_0004
© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 39
Fitters notes Pressure regulators
PS
Identication
All KV pressure regulators carry a label giving the
valve function and type, e.g. CRANKCASE PRESS.
REGULATOR type KVL.
The label also gives the operating range of the
valve and its max. permissible working pressure
(PS/MWP).
A double-ended arrow (“+” and “-“) is printed
on the bottom of the label. Direction “+” (plus)
means higher pressure and “–“ (minus) means
lower pressure.
KV pressure regulators can be used with all
existing refrigerants except ammonia (NH3),
provided valve pressure ranges are respected.
The valve body is stamped with the valve size,
e.g. KVP 15, with an arrow to indicate valve ow
direction.
Ak0_0032
Ak0_0005
Installation
Soldering/brazing
Ensure that piping around KV valves is clean and
well-secured. This will protect valves against
vibration.
All KV pressure regulators must always be
installed so that ow is in the direction of the
arrow.
KV pressure regulators can otherwise be installed
in any position, but they must never be able to
create an oil or liquid lock.
Ak0_0006
During soldering, it is important to wrap a wet
cloth around the valve.
Always point the gas ame away from the valve
so that the valve is never subjected to direct heat.
When soldering, be careful not to leave soldering
material in the valve as this can impair function.
Before soldering a KV valve, be sure that any
pressure gauge insert has been removed. Always
use inert gas when soldering KV valves.
Ak0_0007
Warning!
Alloys in soldering materials and
ux give o smoke which can be
hazardous to health. Please read
gases. It is a good idea to use safety goggles.
Soldering while refrigerant is present in the
system is not recommended.
suppliers’ instructions and follow their safety
precautions. Keep the head away from the smoke
during soldering. Use good ventilation and/or an
extract at the ame and do not inhale smoke and
Aggressive gases might be created which can, for
example, break down the bellows in KV valves or
other parts in the refrigeration system.
40 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006
Fitters notes Pressure regulators
Pressure testing
Evacuation
KV pressure regulators can be pressure-tested
after they have been installed, provided the
test pressure does not exceed the maximum
permissible pressure on the valves.
The maximum test pressure for KV valves is
shown in the table.
During evacuation of the refrigeration system, all
KV valves must be open.
Factory-set KV valves will have the following
positions when supplied:
KVP, closed
KVR, closed
KVL, open
KVC, open
KVD, open
It is therefore necessary to screw the setting
spindle of KVP and KVR right back counterclockwise during system evacuation.
In individual cases it can be necessary to
evacuate from both discharge side and lowpressure side in the refrigeration system.
Evacuation through the pressure gauge connections of KVP, KVR and KVD is not advisable because the orice in these ports are very small.
Type Test pressure, bar
KVP 12 - 15 - 22 28
KVP 28 - 35 25
KVL 12 - 15 - 22 28
KVL 28 - 35 25
KVR 12 - 15 - 22 31
KVR 28 - 35 31
KVD 12 - 15 31
KVC 12 - 15 - 22 31
regulators
Pressure
Ak0_0009
© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 41
Fitters notes Pressure regulators
Setting
KVP evaporating
pressure regulators
When setting KV pressure regulators in refrigeration systems it can be a good idea to use
the factory setting as the starting-out point.
The factory setting for individual pressure
regulators can be found again by measuring
from the top of the valve to the top of the
setting screw.
The table shows the factory setting, the
distance “x” and the pressure change per
revolution of the setting screw for all KV types.
KVP evaporating pressure regulators are always
supplied with a factory setting of 2 bar. Turning
clockwise gives higher pressure and turning
counterclockwise gives lower pressure.
After the system has been in normal operation for
a time, ne adjustment is necessary. Always use a
pressure gauge when making ne adjustments.
If KVP is used for frost protection, ne adjustment
must be made when the system is operating
under minimum load.
Remember to always replace the protective cap
on the setting screw after nal setting.
Type
KVP 12 - 15 - 22
KVP 28 - 35
KVL 12 - 15 - 22
KVL 28 - 35
KVR 12 - 15 -22
KVR 28 - 35
KVD 12 - 15
KVC 12 - 15 - 22
Ak0_0010
Factory
setting
2 bar 13 0.45
2 bar 19 0.30
2 bar 22 0.45
2 bar 32 0.30
10 bar 13 2.5
10 bar 15 1.5
10 bar 21 2.5
2 bar 13 0.45
X mm bar/rev.
KVL crankcase
pressure regulators
KVR + NRD condensing
pressure regulators
Ak0_0011
KVL crankcase pressure regulators are always
supplied with a factory setting of 2 bar.
Turning clockwise gives higher pressure and
turning counterclockwise gives lower pressure.
The factory setting is the point at which KVL
begins to open or where it just closes. Since the
compressor must be protected, the KVL setting is
the max. permissible suction pressure of the
compressor.
The setting must be made using the compressor
suction pressure gauge.
Ak0_0012
In refrigeration systems with KVR + NRD, the
setting of KVR must give a suitable receiver
pressure.
Pressure in the condenser of between 1.4 and 3.0
bar (pressure drop across NRD) higher than the
pressure in the receiver should be acceptable. If it
cannot be accepted, an arrangement with KVR +
KVD must be used.
This setting is best made during operating in a
winter period.
Ak0_0013
42 DKRCC.PF.000.G1.02 / 520H1459 © Danfoss A/S (AC-DSL/MWA), 10 - 2006
Fitters notes Pressure regulators
KVR + KVD condensing
pressure regulators
In refrigeration systems with KVR + KVD, the
condensing pressure must rst be set with KVR
while KVD is closed (setting screw turned back
fully counterclockwise).
Then, KVD must be set to a receiver pressure, e.g.
about 1 bar lower than condensing pressure.
A pressure gauge must be used for this setting
which is best made during operation in a winter
period.
If the condensing pressure is set during summer
operation, one of two procedures can be used:
1) In a newly-installed refrigeration system with
a KVR/KVD setting of 10 bar as the starting
out point, the system can be set by counting
the number of turns on the setting screw.
2) In an existing refrigeration system, where
the KVR/KVD setting is not known, the
starting-out point must rst be established.
The number of turns on the setting screw
Ak0_0014
can then be counted.
Danfoss pressure regulators
Product Used as Opens Pressure range
KVP Evaporating pressure regulator on a rise in pressure on the inlet side 0 - 5.5 bar
KVR Condensing pressure regulator on a rise in pressure on the inlet side 5 - 17.5 bar
regulators
Pressure
KVL Crankcase pressure regulator at a fall in pressure on the outlet side 0.2 - 6 bar
KVC Capacity regulator at a fall in pressure on the outlet side 0.2 - 6 bar
CPCE Capacity regulator at a fall in pressure on the outlet side 0 - 6 bar
NRD Dierential pressure regulator Begins to open when the pressure drop in the
3 - 20 bar
valve is 1.4 bar, and is fully open when the
pressure drop is 3 bar.
KVD Receiver pressure regulator at a fall in pressure on the outlet side 3 - 20 bar
© Danfoss A/S (AC-DSL/MWA), 10 - 2006 DKRCC.PF.000.G1.02 / 520H1459 43
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