SKP70…U.. Air/Gas Ratio Controlling Actuators
Technical Instructions
155-516P25
Rev. 2, December, 1998
Siemens Building Technologies, Inc
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Agency approvals
As safety shut-off valve
UL/429, FM/7400, CGA/3.9,
AGA/Z 21.21 in combination with
VG…U.. series gas valves
UL recognized when used with other valves.
Power supply
Operating voltage
110 to 120 Vac + 10%-15%
220 to 240 Vac + 10%-15%
Operating frequency
50 to 60 Hz + 6%
Power consumption
20 VA
Duty cycle
100%
Operating environment
Ambient operating temperature
15
o
to 140
o
F (-10
o
to 60
o
C)
Mounting position
Optional, with diaphragms in vertical
position but not upside down
Maximum temperature of air and flue
gas at the control connections
140
o
F (60
o
C)
Maximum inlet gas pressure
Same as VG… valve
Physical characteristics
Weight
5.5 lb (2.5 kg)
Enclosure
NEMA 1, 2, 5 and 12 for indoor use
Dimensions
See
Figure 6
Specification for valves
See
gas valve Technical Instruction
No. 155-512P25
Connections
Conduit connection
½-inch NPSM adapter
Gas/air/combustion chamber pressure
connections
¼” NPT
Operating characteristics
Output force
100 lb (450 N)
Maximum stroke
0.7” (18 mm)
Opening time for maximum stroke
12 s
Closing time
< 0.8 s
Control signal
Reference input signal
Combustion air pressure
Control characteristic
integral action
Operation/installation
Setting range of gas to air pressure ratio
0.4:1 to 9:1
Permissible pressures
during operation for accurate control
Min. air presssure: 0.2” w.c.
Max. air pressure: with Pg/Pa <2; 20” w.c.
Max. air pressure: with Pg/Pa >2; 12” w.c.
with higher air pressures use AGA78
Min. downstream gas pressure: 0.4” w.c.
Max. downstream gas pressure: 40” w.c.
Minimum time required for high to low
fire load changes
Approx. 5 s
Permissible leakage test pressure
20 psi
Permissible leakage test vacuum
3 psi
Minimum diameter of impulse pipes
¼” inside diameter (
See
Installation)
Minimum distance between gas
impulse pipe connection and gas
valve outlet
5 x pipe diameter
Auxiliary features
Capacity of auxiliary switch
6 (3) A, 250 Vac
Setting range of auxiliary switch
Full stroke
