Siemens SKP25 Series Owner's manual

Siemens Building Technologies, Inc.
SKP Series
Technical Instructions
Document No. 155-752
SKP25U..
uly 9, 2014
SKP25U.. Pressure Regulating Gas
Valve Actuator with Safet Shut-off
Function
Only when assembled to Series VGU Gas valves
Description
SKP25 pressure regulating electro-hydraulic actuators combine with VG series gas
valve bodies to provide safety shut-off and gas pressure regulation for industrial and
commercial burners. The SKP25 can also be applied as a 1:1 air/gas proportionator
or zero governor.
Since a single valve performs two or more functions, fewer gas train components and
fittings are required. This significantly reduces both the size and weight of the gas train.
In addition, smaller diameter gas valves can be used.
The compact SKP25 actuator opens slowly and closes immediately when power is
interrupted. The modular design allows the SKP25 to be used in combination with all
VG series gas valve bodies from 1/2-inch to 6-inch in size. The actuator is easily
mounted on the square flange of any VG valve with four pre-mounted screws. A
visible position indicator on the front of the actuator displays the entire stroke of the
valve. A light indicates when the actuator is powered.
Features
• UL listed, FM approved, CSA certified for USA and Canada, and ISO 9001
certified. European, Australian and apanese approved versions available.
• Certified as a ventless pressure regulator.
• Safety shut-off function and pressure regulating function in one compact unit.
• Proof of Closure with Over Travel (POC) versions.
• Optional NEMA 4 protection.
• Visual position indication.
• "Power on" indication light
• Quick connect wiring terminals
• Optional adjustable auxiliary switch available.
• Applicable as 1:1 air/gas proportionator or zero governor.
• Accurate pressure control characteristics, and zero offset (droop).
• Modular design with 360
o
actuator rotation for easy field wiring and installation.
• Low, 13.5 VA power consumption.
• Integral regulation leak limiter

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Technical Instructions SKP25U.. Pressure Regulating Gas Valve Actuators
Document Number 155-752
uly 9, 2014
Page 2 Siemens Building Technologies, Inc.
Application
SKP25 series actuators are combined with 1/2-inch to 6-inch VG series gas valve
bodies. VG series gas valves must be ordered separately (See VGU...Technical
Instructions, P/N 155-512P25).
Product Numbers
Table 1.
Product Number
1
Operating
Voltage
Proof of Closure
Switch
4
Auxiliar Switch
4
T pe of Switch
SKP25.011U1
110 to 120 Vac
x – SPDT
SKP25.012U1 x x SPDT SPDT
SKP25.013U1 – – –
SKP25.411U1 2 x – SPDT
SKP25.611U1 3 x – SPDT
SKP25.012U2 220 to 240 Vac x x SPDT SPDT
SKP25.013U2 – – –
NOTES: 1. European, CE certified models are available (see data sheet 7643)
2. High outlet pressure model for 1.5 to 20 psi outlet pressure regulation
3. High bias model for proportionator function with 0" to – 4" WC bias.
4. Proof of closure and auxiliary switches cannot be field installed .
Accessories
Table 2.
Product Number Description
AGA22 Yellow setpoint spring for 6” to 48” WC (1.5 to 10 psi for SKP25.411U1)
AGA23 Red setpoint spring for 40” to 100” WC (8.5 to 20 psi for SKP25.411U1)
AGA25.2 Damping orifice for mounting into vent connection of SKP25.0 or SKP25.4 models
AGA28 Black bias spring to install if SKP25.0 is used as proportionator or zero governor
AGA29 Unpainted setpoint spring for 0” to 8.5” WC (included in SKP25.0 as standard)
AGA66 Sealing gasket to provide NEMA 3, 3R, and 4 protection (for VGG/VGDvalves)
Specifications
Agency approvals
As a safety shut-off valve UL/429, FM/7400, ANSI Z21.21/CSA 6.5 C/I
Agency marks apply only for SKPxx.xxxU actuators
assembled with VGxxx.xxxU series gas valve bodies.
As a pressure regulator ANSI Z21.18/CSA 6.3
Power supply Operating voltage 110 to 120 Vac + 10% to -15%
220 to 240 Vac + 10% to -15%
Operating frequency 50 to 60 Hz +6%
Power consumption 13.5 VA
Duty cycle continuous
Operating environment Ambient operating temperature 5°F to 140°F (-15°C to 60°C)
Mounting position Any position except upside down
Maximum inlet gas pressure Same as VG series

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SKP25U.. Pressure Regulating Gas Valve Actuators Technical Instructions
Document Number 155-752
uly 9, 2014
Siemens Building Technologies, Inc. Page 3
Specifications,
Continued
Physical characteristics
Weight 3.5 lb (1.6 kg)
Enclosure NEMA 1, 2, 5 and 12 for indoor use
NEMA 3, 3R, and 4 with optional AGA66 gasket
Dimensions See Figure 3
Specification for valve bodies See gas valve Technical Instructions,
P/N 155-512P25
Connections Conduit connection Two 1/2-inch NPSM threaded knock-outs
Electrical connection Spring loaded terminals for 14 AWG wires
Gas connection 1/4” NPT
Air connection 1/4” NPT
Gas pressure test connection Hose barb with close-off screw
Operating characteristics Output force 100 lb (450 N)
Maximum stroke 1 inch (26 mm)
Opening time for maximum stroke Varies with valve size, 14 seconds for max. stroke
Closing time < 0.8 seconds
Operation/installation Outlet pressure spring range 0" to 8.5" WC ( standard, unpainted spring, AGA29)
for SKP25.0 models 6" to 48" WC (yellow spring, AGA22)
40" to 100" WC (red spring, AGA23)
for SKP25.411U1 models 1.5 to 10 psi (standard, yellow spring, AGA22)
8.5 to 20 psi (red spring, AGA23)
With air pressure loading for SKP25.4 ± 0.6" WC bias (black spring AGA28)
models or zero governor
or for SKP25.611U1 0" to – 4" WC bias (white spring)
Maximum sensing line pressure 20 psi
Maximum sensing line vacuum 3 psi for SKP25.0 models
Minimum sensing line diameter 1/4" inside diameter
Minimum distance between
sensing line and gas valve outlet 5 times the pipe diameter
Minimum time required for high to low fire 5 seconds
load changes
Auxiliary features Proof of closure switch Non-adjustable
Setting range of auxiliary switch 40% to 100% of stroke
Switch rating 6A/250 Vac resistive; 3A/120 Vac pilot duty

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Technical Instructions SKP25U.. Pressure Regulating Gas Valve Actuators
Document Number 155-752
uly 9, 2014
Page 4 Siemens Building Technologies, Inc.
Operation
(See Figure 1)
Safet Shut-off Function
The electro-hydraulic actuator consists of a cylinder filled with oil, a piston containing an
electric oscillating pump, and a relief system. When power is supplied to the actuator,
the relief system closes, and the pump moves oil from the reservoir into the pressure
chamber. This action causes the piston to move downward in the cylinder, opening the
gas valve. When power to the actuator is interrupted, the relief system opens and the
gas valve closes in less than 0.8 seconds.
A position indicator, visible through the transparent portion of the terminal cover, shows
the entire stroke range of the actuator. A light, which is visible through the lower left
transparent portion of the terminal cover, indicates when the actuator receives power.
An optional, non-adjustable SPDT proof of closure over travel switch signals the closed
position after the gas valve has closed. An optional SPDT auxiliary switch is adjustable
between 40% and 100% of the stroke. The adjustment screw and scale are located on
the right side in the terminal box, and are visible through the transparent portion of the
terminal cover.
Figure 1. SKP25 Operation.
Regulating Function The outlet gas pressure sensing line is connected to the pressure regulator housing.
The outlet pressure acts on the regulator diaphragm. The diaphragm is opposed by an
adjustable setpoint spring force, which represents the desired gas pressure value. The
movement of the diaphragm modulates a hydraulic bypass valve connecting the
pressure chamber to the hydraulic fluid reservoir. When the outlet gas pressure is lower
than the desired value, the bypass valve is closed by the movement of the diaphragm,
causing the actuator piston to open the gas valve. The opposite occurs when the outlet
gas pressure is higher than the desired value; the diaphragm moves to open the bypass
causing the actuator piston to close the gas valve. The movement of the actuator piston
stops once the outlet gas pressure is equal to the setpoint. In this position the bypass
valve is partially open so that the oil flow supplied by the pump is identical to the return
flow. Unlike the conventional direct acting regulators, the SKP25 servo operated
regulating system displays virtually zero droop (offset) across the turndown range.

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SKP25U.. Pressure Regulating Gas Valve Actuators Technical Instructions
Document Number 155-752
uly 9, 2014
Siemens Building Technologies, Inc. Page 5
Regulating Function,
Continued The SKP25.0 models may be applied as a 1:1 air/gas proportionator or as a zero
governor. For either application, the standard spring has to be replaced with AGA28
spring, which allows sdjusting the bias between + 0.6" to –0.6" WC.
For proportionator operation, the air pressure sensing line must be connected to the
port marked “AIR".
High bias model SKP25.611U1 is a 1:1 air/gas proportionator with a factory installed
spring for 0” to -4.0” WC bias.
NOTES: 1. To avoid oscillation, do not oversize the VG valve body. (See
Technical Instructions, P/N 155-512P25.)
2. SKP25.4 models must not be used as proportionators.
Installation
WAR
NING:
• Personal injury or loss of life may occur if procedures are not followed
as specified.
• All installations must be performed by qualified personnel only.
• Do not pull the actuator shaft.
• If minimum gas pressure detection is required, the pressure switch must
be mounted upstream of the regulating gas valve to ensure sufficient
gas pressure before starting the burner. If maximum gas pressure
detection is required the pressure switch must be mounted downstream.
• The AGA66 gasket must be installed between the actuator and the gas
valve body to provide NEMA 3, 3R, and 4 protection rating for VGG
and VGD valves.
• The gas pressure sensing line must be at least 1/4-inch inside diameter.
• The gas pressure sensing line connection must be flush with the inner
wall of the gas pipe in order to sense turbulence free pressure. The gas
sensing line connection should be located at least five pipe diameters
downstream of the valve, elbow, coupling, or other flow disturbing fitting.
Do not use the taps on the valve bod for the gas sensing line
connection since these locations t picall have strong turbulence.
The pressure connection pipe should be as short as possible to allow
the regulator to react to sudden changes.

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Technical Instructions SKP25U.. Pressure Regulating Gas Valve Actuators
Document Number 155-752
uly 9, 2014
Page 6 Siemens Building Technologies, Inc.
Installation,
Continued
• The SKP25 actuator is directly coupled to the VG series valve body by four
pre-mounted 4 mm Allen key screws.
• The square mounting flange can be rotated in steps of 90
o
to provide four different
mounting positions. The SKP25 actuator can be mounted in any position with the
diaphragm vertical, except upside down.
• The actuator can be mounted or replaced while the valve body is under pressure.
• The SKP25 actuator has two knock-outs for the installation of 1/2”-14 NPSM
conduit connections.
• When conduit routing is connected, flexible conduit must be used.
• Liquid tight conduit must be used in combination with AGA66 to provide NEMA 3,
3R, and 4 protection.
• The terminal marked GND, located above the wiring terminals, must be connected
to the electrical ground.
NOTE: Wiring must meet all relevant electrical codes.
Start-up
Regulator
The gas outlet pressure setpoint adjustment screw is located in the center of the
regulator cover. The SKP25.0 models are available with three interchangeable
setpoint springs for an adjustable range of 0” to 100” WC The SKP25.411U models
are available with two interchangeable setpoint springs for an adjustable range of 1.5 to
20 psi. The bias for the SKP25.611U1 model is adjustable from 0 to 4.0" WC (See
Specifications and Table 2). Clockwise rotation of the setpoint adjustment screw
increases the outlet gas pressure. The hexagonal cap must be tightened after the
setpoint screw has been adjusted and may be sealed from tampering by means of a
wire and lead seal.
WARNING:
When firing at maximum burner capacity, ensure that the SKP25 /VG is
not in the fully open position. If this is the case, either the gas valve is sized
too small or the gas supply pressure is too low.
Wiring and
Switch
Adjustment
(See Ter inal
Designations)
• The actuator is equipped with spring-loaded terminals for 14 AWG wires.
• The actuator has two line and two neutral terminals.
• Insert one wire into the opening of the terminal while pressing the lever downward
with a screwdriver or hard object. Make sure that all strands insert into the opening.
• Adjust the auxiliary switch (if provided) according to the wiring diagram on the label
below the terminals (see Figure 2). The adjustment screw and scale are located on
the right side of the terminal box, and are visible through the transparent portion of
the terminal cover.
NOTES: 1. The auxiliary switch is adjustable between 40% and 100% of the stroke.
The factory setting is at 40%.
2. The auxiliary switch must not be used for proof of closure detection or other
safety interlock functions.
3. The Proof of Closure Switch is non-adjustable.

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SKP25U.. Pressure Regulating Gas Valve Actuators Technical Instructions
Document Number 155-752
uly 9, 2014
Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as
design improvements are introduced. Other product or company names mentioned herein may be the trademarks of their respective owners.
© 2005 Siemens Building Technologies, Inc.
SCC
Inc.
1250 Lunt Avenue
Elk Grove Village, IL 60007
U.S.A.
Your feedback is important to us. If you
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Document No. 155-752
Country of Origin: US
Page 7
Service
Terminal
Designations
There are no serviceable parts on the SKP25 series actuators. If inoperative, replace
the actuator. Tag wires before servicing.
GAS0049R1
SKP25.012U.. SKP25.011U.. SKP25.013U..
Figure 2. Terminal Designations.
Dimensions
GAS0052R1
3.20
(81)
2.16
(55)
PRESSURE
TEST PORT
0.35" (8.5) O.D.
6.61
(168)
3.82
(97)
1.30
(33)
1.02
(26)
3.78
(96)
1/2"-14
NPSM
1/4"-18 NPT
FEMALE
1.41
(36)
3.15
(80)
7.95
(202)
1/4"
FEMALE
3.39 SQUARE
(86)
7.87
(200)
8.70
(221)
Figure 3. SKP25U.. Dimensions in Inches, Millimeters in Parentheses.