Siemens ACVATIX PS53 User manual

CE2N4717en
10.11.2011 Building Technologies
s
4717
ACVATIX™
Modulating refrigerant
valves, PS53
MVS661..N
for ammonia (R717) and safety refrigerants
One valve type for expansion, hot-gas and suction throttle applications
Hermetically sealed
Selectable standard interface DC 0/2...10 V or DC 0/4...20 mA
High resolution and control accuracy
Precise positioning control and position feedback signal
Short positioning time (< 1 second)
Closed when deenergized
Robust and maintenance-free
DN 25 with kvs values from 0.10 to 6.3 m³/h
Use
The MVS661..N refrigerant valve is designed for modulating control of refrigerant cir-
cuits including chillers and heat pumps. It is suitable for use in expansion, hot-gas and
suction throttle applications. In addition to ammonia (R717), the valve can handle all
standard safety refrigerants, noncorrosive gases / liquids and CO2(R744). It is not
suited for use with inflammable refrigerants.

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
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Type summary
The refrigeration capacity refers to applications using ammonia.
Product number DN kvs kvs reduced pmax Q0E Q0H Q0D SNA Pmed
[m3/h] [m3/h] [MPa] [kW] [kW] [kW] [VA] [W]
MVS661.25-016N 25 0,16 0,10 95 10 2
MVS661.25-0.4N 25 0,40 0,25 245 26 5
MVS661.25-1.0N 25 1,0 0,63 610 64 12
MVS661.25-2.5N 25 2,5 1,6 1530 159 29
MVS661.25-6.3N 25 6,3 4,0
2,5
3850 402 74
22 12
kvs = Nominal flow rate of refrigerant through the fully open valve (H100) at a differential pressure
of 100 kPa (1 bar) to VDI 2173
If required kvs-value and refrigeration capacity Q0can be reduced to 63 %, refer to «kvs re-
duction» on page 3
∆pmax = Maximum permissible differential pressure across the control path A AB of the valve,
valid for the entire actuating range of the motorized valve
Q0E = Refrigeration capacity in expansion applications
Q0H = Refrigeration capacity in hot-gas bypass applications
Q0D = Refrigeration capacity in suction throttle applications and ∆p = 0.5 bar
SNA = nominal apparent power for selecting the transformer
Pmed = typical power consumption
The pressure drop across evaporator and condenser is assumed to be 0.3 bar each, and 1.6 bar up-
stream of the evaporator (e.g. spider).
The capacities specified are based on superheating by 6 K and subcooling by 2 K.
Product number DN kvs
[m3/h]
ASR0.16N 25 0,16
ASR0.4N 25 0,40
ASR1.0N 25 1,0
ASR2.5N 25 2,5
ASR6.3N 25 6,3
The refrigeration capacity for various refrigerants and operating conditions can be cal-
culated for the 3 types of application using the tables starting from page 12.
For accurate valve sizing, the valve selection program "Refrigeration VASP" is recom-
mended.
Ordering
Valve body and magnetic actuator form one integral unit and cannot be separated.
Should the valve’s electronics become faulty, the entire electronics housing is to be
replaced by spare part ASR61, which is supplied complete with Mounting Instructions
(74 319 0270 0).
See table on page 16.
If plant is resized, or should excessive wear impact the valve’s perform-
ance, a new valve insert ASR…N will restore the valve’s characteristics to
its original specifications.
The valve insert is supplied complete with Mounting Instructions
(74 319 0486 0).
Accessories
Valve insert ASR..N
Example: Product number Stock number Designation Quantity
MVS661.25-0.4N MVS661.25-0.4N Refrigerant valve 1
Spare parts
Replacement electron-
ics ASR61
Rev. no.
Valve insert ASR..N

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Technical design / functions
4 selectable standard signals for setpoint and measured value
DIL switch to reduce the kvs value to 63 % of the nominal value
Potentiometer for adjustment of minimum stroke for suction throttle applications
Automatic stroke calibration
Forced control input for "Valve closed" or "Valve fully open”
LED for indicating the operating state
The MVS661..N refrigerant valve can be driven by Siemens or third-party controllers
that deliver a DC 0/2...10 V or DC 0/4...20 mA output signal.
For optimum control performance, we recommend a 4-wire connection between con-
troller and valve. When operating on DC voltage, a 4-wire connection is mandatory!
The valve stroke is proportional to the control signal.
If the positioning signal is interrupted, or in the event of a power failure, the valve’s
return spring will automatically close control path 1 3.
4716Z15
2on
1234
G0 G Y UMZC
1
3
45
1 Connection terminals
2 LED for indication of operating state
3 Minimal stroke setting potentiometer Rv
4 Autocalibration
5 DIL switches for mode control
Switch Function ON / OFF Description
ON Current [mA]
1
ON
Positioning signal Y
OFF Voltage [V] 1)
ON DC 2…10 V, 4…20 mA
2
ON
Positioning range Y and U
OFF DC 0…10 V, 0…20 mA 1)
ON Current [mA]
3
ON
Position feedback U
OFF Voltage [V] 1)
ON 63 %
4
ON
Nominal flow rate kvs
OFF 100 % 1)
1) Factory setting
When kvs reduction (DIL switch 4 in
position ON) the stroke will be lim-
ited to 63 % mechanical stroke. 63
% of full stroke then corresponds to
an input / output signal of 10 V.
If, in addition, the stroke is limited
to 80 %, for example, the minimum
stroke will be
0.63 x 0.8 = 0.50 of full stroke.
Features and benefits
Control
Spring return function
Operator controls and
indicators in the
electronics housing
Configuration of
DIL switches
kvs-reduction

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80 %
100 %
4716D01en
0 %
0 % 100 %
Y-inp ut
Stroke
In the case of the suction throttle valve, it is
essential that a minimum stroke limit be
maintained to ensure compressor cooling
and efficient oil return. This can be
achieved with a reinjection valve, a bypass
line across the valve, or a guaranteed
minimum opening of the valve. The mini-
mum stroke can be defined via the control-
ler and control signal Y, or it can be set
directly with potentiometer Rv.
The factory setting is zero (mechanical stop in counterclockwise direction, CCW). The
minimum stroke can be set by turning the potentiometer clockwise (CW) to a maximum
of 80 % kvs.
Under no circumstances must potentiometer Rv be used to limit the stroke on
expansion applications. It must be possible to close the valve fully.
ZC – Function
no function fully open closed
ConnectionsTransfer
GG G
function
ZC not connected
Valve will follow the Y-signal
Minimum stroke set-ting
with potentiometer Rv pos-
sible
ZC connected to G
Valve will fully open control
path A AB
ZC connected to G0
Valve will close control path
A AB
1. Forced control signal ZC
2. Signal input Y and/or minimum stroke set-ting with potentiometer Rv possible
The printed circuit board of the MVS661..N has a slot to facilitate calibration.
To make the calibration, insert a screwdriver in the slot so that the contacts
inside are connected. As a result, the valve will first be fully closed and then
fully opened.
Calibration matches the electronics to the valve’s mechanism.
During the calibration process the green LED flashes for about 10 seconds;
refer to "Indication of operating state" (page 5).
01124
MVS661..N refrigerant valves are supplied fully calibrated.
Execute a calibration after replacing the electronics, when the red LED is on or
when the valve is leaking (at seat).
Minimum stroke set-
ting
Attention
Forced control input ZC
Signal priority
Calibration
When is a calibration
required?

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LED Indication Function Remarks, troubleshooting
Green Lit
Control mode Automatic operation; everything o.k.
Flashing
Calibration in pro-
gress
Wait until calibration is finished
(green or red LED will be lit)
Red Lit
Calibration error
Internal error
Recalibrate (operate button in opening 1x)
Replace electronics module
Flashing
Mains fault Check mains network (outside the frequency or
voltage range)
Both Dark
No power supply
Electronics faulty
Check mains network, check wiring
Replace electronics module
The 4-wire connection should always be given preference!
SNA PMED IFWire cross-section [mm2]
1.5 2.5 4.0 2)
Product number [VA] [W] [A] max. cable length L [m]
MVS661..N 22 12 1.6…4 A 65 110 160
MVS661..N 22 12 1.6…4 A 20 35 50
SNA = nominal apparent power for selecting the transformer
PMED = typical power consumption
IF= required slow fuse
L = max. cable length; with 4-wire connections, the max. permissible length of the separate 1.5 mm2
copper positioning signal wire is 200 m
1) All information at AC 24 V
2) With 4 mm2electrical wiring reduce wiring cross-section for connection inside valve to 2.5 mm2.
Sizing
For straightforward valve sizing, refer to the tables for the relevant application (from
page 9).
For accurate valve sizing, we recommend to make use of the valve sizing software
"Refrigeration VASP", available from your local Siemens office.
The refrigeration capacity Q0is calculated by multiplying the mass flow by the specific
enthalpy differential found in the h, log p-chart for the relevant refrigerant. To help de-
termine the refrigeration capacity more easily, a selection chart is provided for each
application (from page 10). With direct or indirect hot-gas bypass applications, the en-
thalpy differential of Qc(the condenser capacity) must also be taken into account when
calculating the refrigeration capacity.
If the evaporating and/or condensing temperatures are between the values shown in
the tables, the refrigeration capacity can be determined with reasonable accuracy by
linear interpolation (refer to the application examples from page 11).
At the operating conditions given in the tables, the permissible differential pressure
pmax (25 bar) across the valve is within the admissible range for these valves.
If the evaporating temperature is raised by 1 K, the refrigeration capacity increases by
about 3 %. If, by contrast, subcooling is increased by 1 K, the refrigeration capacity
increases by about 1 to 2 % (this applies only to subcooling down to approximately
8 K).
Engineering notes
Depending on the application, it may be necessary to observe additional Installation
Instructions and fit appropriate safety devices (e.g. pressurestats, full motor protection,
etc.).
In order not to damage the seal inside the valve insert, the plant must be vented on the
low-pressure side after the pressure test has been made (valve port AB), or the valve
Indication of operating
state
Connection type 1)
4-wire connection
3-wire connection
Notes
Warning

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must be fully open during the pressure test and during venting (power supply con-
nected and positioning signal at maximum or forced opening by G ZC).
To prevent the formation of flash gas on expansion applications, the velocity of the
refrigerant in the fluid pipe must not exceed 1 m/s. To assure this, the diameter of the
fluid pipe must under certain circumstances be greater than the nominal size of the
valve.
1 = evaporator
2 = compressor
3 = condenser
4 = expansion valves
a) The differential pressure over reduction must be less than half the differential
pressure ΔpFL.
b) The inlet path between diameter reduction and expansion valve inlet
Must straight for at least 600 mm
May not contain any valves
A filter / dryer must be mounted upstream of the expansion valve.
The valve is not explosion-proof.
Mounting notes
The valve should be mounted and commissioned by qualified staff. The same applies
to the replacement electronics and the configuration of the controller (e.g. SAPHIR or
PolyCool).
90°
4716Z16
90°
The refrigerant valves can be mounted in any orientation, but
upright mounting is preferable.
Arrange the pipework in such a way that the valve is not lo-
cated at a low point in the plant where oil can collect.
The pipes should be fitted in such a way that the alignment
does not distort the valve connections. Fix the valve body so
that that it cannot vibrate. Vibration can lead to burst connec-
tion pipes.
Before soldering the pipes, ensure that the direction of flow
through the valve is correct.
The pipes must be soldered with care. To avoid dirt and the
formation of scale (oxide), inert gas is recommended for sol-
dering.
The flame should be large enough to ensure that the junction
heats up quickly and the valve does not get too hot.
The flame should be directed away from the valve.
During soldering, cool the valve with a wet cloth, for example,
to ensure that it does not become too hot.
Expansion application
Engineering notes

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Port B must be sealed off when a 2-port valve (AB A) is
used.
The valve body and the connected pipework should be lagged.
The actuator must not be lagged.
The valve is supplied complete with Mounting Instructions 74 319 0707 0.
Maintenace notes
The refrigerant valve is maintenance-free.
If the valve’s interior is subjected to great wear, the valve can be repaired by replacing
the ASR..N valve insert.
Disposal
The actuator contains electrical and electronic components and must not be disposed
of together with domestic waste.
Legislation may demand special handling of certain components, or it may be sensible
from an ecological point of view
Current local legislation must be observed.
Warranty
Application-specific technical data must be observed.
If specified limits are not observed, Siemens Building Technologies / CPS Prod-
ucts will nor assume any responsibility.
Technical data
Functional actuator data
Power supply Extra low-voltage only (SELV, PELV)
AC 24 V Operating voltage AC 24 V ± 20 %
Frequency 45...65 Hz
Typical power consumption Pmed 12 W
Stand by < 1 W (valve closed)
Rated apparent power SNA 22 VA (for selecting the transformer)
Required fuse IF1,6…4 A, slow
DC 24 V Operating voltage DC 20…30 V
Current draw 0,5 A / 2 A (max.)
Signal inputs Positioning signal Y DC 0/2…10 V or DC 0/4…20 mA
Impedance DC 0/2…10 V 100 k// 5nF (load < 0,1 mA)
DC 0/4…20 mA 240 // 5nF
Forced control ZC
Input impedance 22 k
Close valve (ZC connected to G0) < AC 1 V; < DC 0,8 V
Open valve (ZC connected to G) > AC 6 V; > DC 5 V
No function (ZC not wired) Positioning signal Y active
Signal outputs Position feedback U Voltage DC 0/2…10 V; load resistance 500 
Current
DC 0/4…20 mA; load resistance 500 
Stroke measurement
Nonlinearity
Inductive
± 3 % of end value
Positioning time Positioning time < 1 s
Electrical connection Cable entry 3 x Ø 17 mm (for M16)
Minimal wire cross-section 0.75 mm2
Maximum cable length Refer to "Connection type", page 5
Repair

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Functional valve data Permissible operating pressure max. 5.3 MPa (53 bar) 1)
Differential pressure Δpmax 2.5 MPa (25 bar)
Valve characteristic (stroke, kv) linear (to VDI / VDE 2173)
Leakage rate
(internally across seat)
max. 0,002 % kvs resp.
max. 1 Nl/h gas at p = 4 bar
Shut/off function, like solenoid normally closed (NC)
function
External seal hermetically sealed!
Permissible media Ammonia (R717), CO2 (R744) and all safety refrig-
erants (R22, R134a, R404A, R407C, R507, etc);
Not suited for use with inflammable refrigerants
Medium temperature -40...120 °C; max. 140 °C for 10 min
Stroke resolution H / H100 1 : 1000 (H = stroke)
Hysteresis typically 3 %
Mode of operation modulating
Position when deenergized control path A AB closed
Mounting position
2) Upright to horizontal
Materials Valve body steel / CrNi steel
Seat / piston CrNi steel
Sealing disk / O-rings PTFE / CR (chloroprene)
Dimensions and weight Dimensions refer to "Dimensions", page 10
Weight 5.17 kg
Pipe connections Solder (weld-on-ends) Referring to EN 1092-1 and ASME B16.25 sche-
dule 40
Inner diameter 22.4 mm
Outer diameter 33.7 mm
Norms and standards CE conformity
to EMV-requirements 2004/108/EC
Immunity EN 61000-6-2:[2005] Industrial
3)
Emission EN 61000-6-3:[2007] Residential
Electrical safety EN 60730-1
Protection class Class III to EN 60730
Pollution degree Degree 2 to EN 60730
Housing protection
Upright to horizontal IP65 to EN 60529 2)
Vibration
4) EN 60068-2-6
5 g acceleration, 10...150 Hz, 2.5 h
(5 g horizontal, max. 2 g upright)
Conform to UL standards
CSA, Canada
C-tick
UL 873
C22.2 No. 24
N 474
Environmental compatibility ISO 14001 (Environment)
ISO 9001 (Quality)
SN 36350 (Environmentally compatible products)
RL 2002/95/EG (RoHS)
Permissible operating pressure PED 97/23/EC
Pressure accessories As per article 1, section 2.1.4
Fluid group 1 Without CE-marking as per article 3, section 3
(sound engineering practice)
1) To EN 12284 tested with 1,43 x operating pressure at 76 bar
2) At 45 °C < Tamb < 55 °C and 80 °C < Tmed < 120 °C the valve must be installed on its side to
avoid shortening the service life of the valve electronics
3) Transformer 160 VA (e.g. Siemens 4AM 3842-4TN00-0EA0)
4) In case of strong vibrations, use high-flex stranded wires for safety reasons.

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General
environmental conditions
Operation
EN 60721-3-3
Transport
EN 60721-3-2
Storage
EN 60721-3-1
Climatic conditions Class 3K6 Class 2K3 Class 1K3
Temperature –25...55 °C –25...70 °C –5...45 °C
Humidity 10...100 % r. h. < 95 % r. h. 5...95 % r. h.
Connection terminals
G
Operating voltage AC / DC 24 V
U
G
DC 0 ... 10 V / 2 ... 10 V
0 ... 20 mA / 4 ... 20 mA
DC 0 ... 10 V / 2 ... 10 V
0 ... 20 mA / 4 ... 20 mA
Control signal
Measuring neutral (= G0)
Position feedback signal
Override input
Connection diagrams
Common Transformer Separate Transformer
G
U
G
U
G
Common Transformer Separate Transformer
G
U
G
U
G
UIndication of valve position (only if required). DC 0...10 V →0...100 % volumetric flow V100
Twisted pairs. If the lines for AC 24 V power supply and the DC 0...10 V (DC 2...10 V,
DC 0... 20 mA, DC 4... 20 mA) positioning signal are routed separately, the AC 24 V line need
not be twisted.
Piping must be connected to potential earth!
Factory setting: Valve characteristics equal-percentage, positioning signal DC 0...10 V.
Details see "Configuration DIL switches", page 3.
See "Calibration", page 4.
Terminal assignment
for controller with
4-wire connection
(to be preferred!)
Terminal assignment
for controller with
3-wire connection
Warning
DIL switch
Calibration

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Dimensions
Dimensions in mm
210 min. 100
124
74
284
ø 22.4 ø 33.7
160
ø 60
4717M01
Valve sizing with correction factor
The applications and correction tables on the following pages are designed for help
with selecting the valves. To select the correct valve, the following data is required:
Application
Expansion (starting on page 11)
Hot-gas (starting on page 13)
Suction throttle (starting on page 15)
Refrigerant type
Evaporating temperature to[ °C]
Condensing temperature tc[ °C]
Refrigeration capacity Q0[kW]
To calculate the nominal capacity, use the following formula:
kvs [m³/h] = Q0[kW] / K…* *K… for Expansion = KE
for hot-gas = KH
for suction throttle = KS
The theoretical kvvalue for the nominal refrigeration capacity of the plant should not
be less than 50 % of the kvs value of the selected valve
For accurate valve sizing, the valve selection program "Refrigeration VASP" is rec-
ommended

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
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The application examples on the following pages deal with the principles only. They do
not include installation-specific details such as safety elements, refrigerant collectors,
etc.
Use of the MVS661..N as an expansion valve
Observe engineering notes page 5
Typical control range 20...100 %.
Increased capacity through better use of the evaporator
The use of 2 or more compressors or compressor stages significantly increases
efficiency with low loads
Especially suitable for fluctuating condensing and evaporating pressures
40153A
1
2
4
3
1 = MVS661..N
2 = evaporator
3 = compressor
4 = condenser
Electronic superheat control is achieved by using additional control equipment (e.g.
PolyCool).
Refrigerant R717C; Q0= 205 kW; to= -5 °C; tc= 35 °C
The correct kvs value for the MVS661..N valve needs to be determined.
The important section of table KE for R717 is the area around the working point. The
correction factor KE relevant to the working point should be determined by linear inter-
polation from the 4 guide values.
In practice, the KE, KH or KS value can be estimated because the theoretical kvs-value
ascertained will be rounded off by up to 30 % to 1 of the 10 available kvs-values. So you
can proceed directly with Step 4.
Step 1: For tc= 35 °C, calculate the value for to= -10 °C between values 20 °C and
40 °C in the table; result: 574
Step 2: For tc= 35 °C, calculate the value for to= 0 °C between values 20 °C and 40
°C in the table; result: 553
Step 3: For to= -5 °C, calculate the value for tc= 35 °C between correction factors
574 and 553; calculated in steps 1 and 2; result: 450
Step 4: Calculate the theoretical kvs value; result: 0.46 m3/h
Step 5: Select the valve; the valve closest to the theoretical kvs value is the
MVS661.25-0.4N
Step 6: Check that the theoretical kvs value is greater than 50 % of nominal kvs value
KE R717C to= –10 °C to= 0 °C Interpolation at tc= 35 °C
tc= 20 °C 481 376 481 + [(605 - 481) x (35 - 20) / (40 - 20)] 574
tc= 35 °C 574 553
tc= 40 °C 605 612 376 + [(612 - 376) x (35 - 20) / (40 - 20)] 553
Interpolation at to= -5 °C
574 +[(553 - 574) x (-5 - 0) / (-10 - 0)] 450
kvs theoretical = 205 kW / 450 = 0.46 m3/h
Valve MVS661.25-0.4N is suitable, since: 0.46 m3/h / 0.4 m3/h x 100 % = 115 % (> 50 %)
a) Refrigerant valve MVS661..N for capacity control of a dry expansion evaporator.
Note
Capacity optimization
Application example
Note on interpolation
Capacity control

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
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4717Z07
+
-
MVS661..N
Suction pressure and temperature are moni-
tored with a mechanical capacity controller
and reinjection valve.
Typical control range 0...100 %
Energy-efficient operation with low loads
Ideal control of temperature and dehumidi-
fication
b) Refrigerant valve MVS661..N for capacity control of a chiller.
4717Z08
+
-
MVS661..N
Typical control range 10...100 %
Energy-efficient operation with low loads
Allows wide adjustment of condensing and
evaporating temperatures
Ideal for use with plate heat exchangers
Very high degree of frost protection
A larger valve may be required for low-load operation than is needed for full load condi-
tions. To ensure that the selected valve will not be too small for low loads, sizing should
take account of both possibilities.
R717 R22
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 324 265 124 00 82 68 37
20 481 488 494 481 376 124 20 101 104 107 105 81 18
40 581 590 598 605 612 618 40 108 111 114 118 120 123
60 662 673 683 693 701 708 60 104 108 112 116 119 122
R744 R134a
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
-20 226 149 00 27
00 262 264 241 166 20 71 74 77 66 43
20 245 247 247 246 213 40 74 78 81 85 89 92
60 67 72 76 81 85 89
R402A R401A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 73 69 50 00 31
20 77 81 85 88 74 35 20 80 83 85 72 46
40 71 75 80 84 88 91 40 87 90 94 97 101 102
60 50 55 60 65 69 74 60 85 89 94 98 102 106
R407A R404A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 79 67 40 00 69 63 44
20 91 95 98 102 82 30 20 70 74 78 81 68 30
40 89 94 98 102 106 110 40 61 65 70 74 78 81
60 72 77 82 87 92 96 60 36 41 46 51 55 59
R407C R407B
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 79 65 31 00 72 66 45
20 98 101 105 108 85 21 20 77 80 84 88 75 34
40 100 104 109 113 117 121 40 69 74 78 83 87 91
60 87 93 98 103 108 113 60 46 51 56 61 66 70
Note
Correction table KE
Expansion valve

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R507 R410A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 72 66 47 00 116 117 91 12
20 78 81 83 86 71 33 20 125 130 133 137 120 69
40 74 78 81 84 87 90 40 119 124 129 133 137 140
60 53 57 61 64 68 71 60 90 96 101 106 110 114
With superheat = 6 K With subcooling = 2 K ∆p upstream of evaporator = 1.6 bar
∆p condenser = 0.3 bar ∆p evaporator = 0.3 bar
Use of the MVS661..N as a hot-gas valve
The control valve throttles the capacity of a compressor stage. The hot gas passes
directly to the evaporator, thus permitting capacity control in the range from 100 %
down to approximately 0 %.
Suitable for use in large refrigeration
systems in air conditioning plant, to pre-
vent unacceptable temperature fluctua-
tions between the compressor stages.
With low loads, the evaporating and condensing pressures can fluctuate depending on
the type of pressure control. In such cases, evaporating pressure increases and con-
densing pressure decreases. Due to the reduction in differential pressure across the
fully open valve, the volumetric flow rate will drop – the valve is undersized. This is why
the effective pressures must be taken into account when sizing the valve for low loads.
Refrigerant R507; 3 compressor stages; Q0= 75 kW; to= 4 °C; tc= 40 °C
Part load Q0per stage = 28 kW; to= 4 °C; tc= 23 °C
KH R507 to= 0 °C to= 10 °C Interpolation at tc= 23 °C
tc= 20 °C 14,4 9,0 14,4 + [(22,4 - 14,4) x (23 - 20) / (40 - 20)] 15,6
tc= 23 °C 15,6 11,0
tc= 40 °C 22,4 22,0 9,0 + [(22,0 - 9,0) x (23 - 20) / (40 - 20)] 11,0
Interpolation at to= 4 °C
15,6 + [(11,0 - 15,6) x (4 - 0) / (10 - 0)] 13.8
kvs theoretical = 28 kW / 13,8 = 2,03 m3/h
Valve MVS661.25-2.5N is suitable, since: 2.03 m3/h / 2.5 m3/h x 100 % = 81 % (> 50 %)
The control valve throttles the capacity of one compressor stage. The gas is fed to
the suction side of the compressor and then cooled using a reinjection valve. Ca-
pacity control ranges from 100 % down to approximately 10 %.
Suitable for large refrigeration systems on
air conditioning applications with several
compressors or compressor stages, and
where the evaporator and compressor are
some distance apart (attention must be
paid to the oil return).
Indirect hot-gas
bypass application
Application example
Direct hot-gas bypass
application

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
Building Technologies 10.11.2011
R717 R22
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 20 19 14 00 8,9 8,4 6,3
20 38 38 38 38 35 19 20 15,3 15,1 14,8 14,6 13,2 6,5
40 67 66 65 64 64 63 40 24,2 23,7 23,2 22,8 22,4 22,1
60 110 107 105 103 102 100 60 35,7 34,7 33,8 33,0 32,3 31,7
R744 R134a
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
-20 38,1 30,5 00 4,5
00 60,9 59,8 58,1 47,1 20 9,8 9,6 9,5 9,2 7,4
20 87,3 84,9 82,5 80,2 76,1 40 15,9 15,6 15,3 15,1 14,9 14,7
60 23,8 23,2 22,7 22,3 21,9 21,6
R402A R401A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 9,7 9,5 8,3 00 4,7
20 15,9 15,7 15,4 15,2 14,5 9,3 20 10,2 10,0 9,9 9,5 7,6
40 23,7 23,2 22,7 22,4 22,0 21,7 40 16,9 16,6 16,2 16,0 15,8 15,6
60 31,5 30,7 29,9 29,2 28,7 28,1 60 25,9 25,2 24,6 24,1 23,7 23,3
R407A R404A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 8,9 8,6 6,7 00 9,4 9,2 7,8
20 15,7 15,4 15,2 15,0 14,1 8,0 20 15,2 15,0 14,8 14,6 13,9 8,6
40 24,9 24,4 23,9 23,5 23,1 22,8 40 22,3 21,8 21,5 21,1 20,9 20,6
60 35,9 34,9 34,0 33,2 32,6 32,0 60 28,8 28,0 27,4 26,8 26,4 25,9
R407C R407B
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 8,6 8,1 5,9 00 9,0 8,8 7,4
20 15,3 15,0 14,8 14,6 13,6 7,0 20 15,3 15,1 14,8 14,7 14,0 8,8
40 24,7 24,2 23,7 23,3 22,9 22,6 40 23,3 22,8 22,4 22,0 21,7 21,5
60 36,3 35,3 34,4 33,6 33,0 32,4 60 31,6 30,7 30,0 29,3 28,8 28,3
R507 R410A
tc\ to-40 -30 -20 -10 0 10 tc\ to-40 -30 -20 -10 0 10
00 9,8 9,5 8,1 00 14,5 14,3 13,2 6,2
20 16,1 15,8 15,5 15,3 14,4 9,0 20 24,2 23,7 23,3 23,0 22,1 15,9
40 24,5 23,8 23,3 22,8 22,4 22,0 40 36,8 35,9 35,1 34,4 33,7 33,1
60 33,1 31,8 30,7 29,8 29,0 28,3 60 50,0 48,5 47,2 46,0 44,9 43,8
With superheat = 6 K With subcooling = 2 K ∆p upstream of evaporator = 1.6 bar
∆p condenser = 0.3 bar ∆p evaporator = 0.3 bar
Correction table KH
Hot-gas valve

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
Building Technologies 10.11.2011
Use of the MVS661..N as a suction throttle valve
Typical control range 50...100 %.
Minimum stroke limit control:
To ensure optimum cooling of the compressor,
either a capacity controller must be provided for
the compressor, or a minimum stroke must be set
via the valve electronics.
The minimum stroke can be limited to a maximum of 80 %. At zero load, the minimum
stroke must be sufficient to ensure that the minimum gas velocity in the suction line is >
0.7 m/s and that the compressor is adequately cooled.
As the control valve closes, the evaporating temperature rises and the air-cooling effect
decreases continuously. The electronic control system provides demand-based cooling
without unwanted dehumidification and costly retreatment of the air.
The pressure at the compressor inlet falls and the power consumption of the compres-
sor is reduced. The energy savings to be anticipated with low loads can be determined
from the compressor selection chart (power consumption at minimum permissible suc-
tion pressure). Compressor energy savings of up to 40 % can be achieved.
The recommended differential pressure ∆pV100 across the fully open control valve
is between 0.15 < ∆pV100 < 0.5 bar.
Refrigerant R134A; Q0= 9,5 kW; to= 4 °C; tc= 40 °C;
Differential pressure across MVS661..N: pV100 = 0,25 bar
In this application example, to, tcand ∆pV100 are to be interpolated.
KS R134a to= 0 °C to= 10 °C Interpolation at to= 4 °C
0,15 / 20 2.2 2.7 2,2 + [(2,7 - 2,2) x (4 - 0) / (10 - 0)] 2,4
0,15 / 50 1.7 2.1 1,7 + [(2,1 - 1,7) x (4 - 0) / (10 - 0)] 1,9
0,45 / 20 3.6 4.5 3,6 + [(4,5 - 3,6) x (4 - 0) / (10 - 0)] 4,0
0,45 / 50 2.7 3.4 2,7 + [(3,4 - 2,7) x (4 - 0) / (10 - 0)] 3,0
to= 4 °C tc= 20 °C tc= 50 °C Interpolation at tc= 40 °C
pv100 0,15 2.4 1.9 2,4 + [(1,9 - 2,4) x (40 - 20) / (50 - 20)] 2,1
pv100 0,45 4.0 3.0 4,0 + [(3,0 - 4,0) x (40 - 20) / (50 - 20)] 3,3
tc= 40 °C pv100 0.15 pv100 0.45 Interpolation at pv100 0,25
2.1 3.3 2,1 + [(3,3 - 2,1) x (0,25 - 0,15) / (0,45 - 0,15)] 2,5
kvs theoretical = 9,5 kW / 2,5 = 3,8 m3/h
Valve MVS661.25-6.3N is suitable, since 3.8 m3/h / 6.3 m3/h x 100 % = 60 % (> 50 %)
It is recommended that the kvs value be set to 63 % = 4 m3/h
509 41 A
+
–
Typical control range 10...100 %.
The capacity controller ensures that the com-
pressor is adequately cooled, making it unnec-
essary to set a minimum stroke in the refriger-
ant valve.
Application example

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Siemens Modulating refrigerant valves, PS53 CE2N4717en
Building Technologies 10.11.2011
tcR717 tcR22
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 2.7 3.7 4.8 6.0 7.3 8.8 0.15 / 20 1,2 1,5 1,9 2,4 2,9 3,4
0.15 / 50 2.3 3.2 4.2 5.2 6.4 7.8 0.15 / 50 0,9 1,2 1,5 1,9 2,3 2,7
0.45 / 20 3.2 5.2 7.4 9.7 12.1 14.8 0.45 / 20 1,5 2,3 3,0 3,9 4,8 5,7
0.45 / 50 2.8 4.6 6.5 8.5 10.7 13.1 0.45 / 50 1,2 1,8 2,4 3,0 3,8 4,6
tcR152A tcR134a
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 0,9 1,3 1,7 2,2 2,7 3,3 0.15 / 20 0,7 1,0 1,4 1,8 2,2 2,7
0.15 / 50 0,7 1,0 1,4 1,7 2,2 2,7 0.15 / 50 0,5 0,7 1,0 1,3 1,7 2,1
0.45 / 20 1,0 1,5 2,4 3,3 4,3 5,3 0.45 / 20 0,7 1,2 1,9 2,7 3,6 4,5
0.45 / 50 0,7 1,2 1,9 2,6 3,5 4,4 0.45 / 50 0,5 0,9 1,4 2,0 2,7 3,4
tcR402A tcR401A
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 1,1 1,4 1,8 2,2 2,7 3,3 0.15 / 20 0,8 1,1 1,5 1,9 2,3 2,9
0.15 / 50 0,7 0,9 1,2 1,5 1,8 2,3 0.15 / 50 0,6 0,8 1,1 1,5 1,8 2,3
0.45 / 20 1,5 2,2 2,9 3,7 4,6 5,6 0.45 / 20 0,8 1,3 2,1 2,9 3,7 4,7
0.45 / 50 0,9 1,4 1,9 2,4 3,1 3,8 0.45 / 50 0,6 1,0 1,6 2,3 3,0 3,7
tcR407A tcR404A
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 1,0 1,4 1,8 2,3 2,9 3,5 0.15 / 20 1,0 1,3 1,7 2,2 2,7 3,3
0.15 / 50 0,7 1,0 1,3 1,6 2,1 2,6 0.15 / 50 0,6 0,8 1,1 1,4 1,7 2,1
0.45 / 20 1,3 2,0 2,9 3,8 4,7 5,9 0.45 / 20 1,4 2,1 2,8 3,6 4,5 5,5
0.45 / 50 0,9 1,4 2,0 2,7 3,4 4,3 0.45 / 50 0,8 1,2 1,7 2,3 2,9 3,6
tcR407C tcR407B
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 1,0 1,4 1,8 2,3 2,9 3,5 0.15 / 20 1,0 1,3 1,7 2,2 2,7 3,3
0.15 / 50 0,7 1,0 1,3 1,7 2,1 2,6 0.15 / 50 0,6 0,8 1,1 1,4 1,8 2,2
0.45 / 20 1,3 2,0 2,8 3,8 4,8 5,9 0.45 / 20 1,3 2,0 2,7 3,5 4,5 5,5
0.45 / 50 0,9 1,4 2,1 2,8 3,5 4,4 0.45 / 50 0,8 1,2 1,7 2,3 3,0 3,8
tcR507 tcR410A
pv100 \ to-40 -30 -20 -10 0 10 pv100 \ to-40 -30 -20 -10 0 10
0.15 / 20 1.1 1.4 1.8 2.3 2.7 3.3 0.15 / 20 1,5 2,0 2,5 3,0 3,6 4,4
0.15 / 50 0.7 1.0 1.3 1.6 1.9 2.4 0.15 / 50 1,0 1,3 1,7 2,1 2,6 3,1
0.45 / 20 1.6 2.2 2.9 3.7 4.6 5.6 0.45 / 20 2,3 3,1 4,0 5,0 6,1 7,4
0.45 / 50 1.1 1.5 2.0 2.6 3.2 4.0 0.45 / 50 1,6 2,1 2,8 3,5 4,4 5,3
With superheat = 6 K With subcooling = 2 K ∆p upstream of evaporator = 1.6 bar
∆p condenser = 0.3 bar ∆p evaporator = 0.3 bar
Revision numbers
Product number Valid from rev. no.
MVS661.25-016N A
MVS661.25-0.4N A
MVS661.25-1.0N A
MVS661.25-2.5N A
MVS661.25-6.3N A
Correction table KS
Suction throttle valve
2011 Siemens Switzerland Ltd Sub
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