Technical Instructions
QFM81 Series Duct Hygrostats
Document Number 155-707
April 21, 2010
Page 4
Siemens Industry, Inc.
Specifications
Setpoint range
15 to 95% rh
Control mode
On / off
Switching differential
Approximately 4% rh (fixed)
Type of switch
Potential-free microswitch (SPDT)
Contact rating
Maximum
5 (3) A, 24 Vac/Vdc
Minimum
100 mA, 24 Vac/Vdc
Temperature influence
Compensated
Long-term stability
Approximately
−
1.5% rh/a
Balancing
At 55% rh, 73°F (23°C)
Time constant (v = 0.2 m/s)
Approximately 3 minutes
Permissible air velocity
10 m/s
Permissible ambient temperature
Operation
32°F to 158°F (0°C to 70°C)
Storage/transport
–22°F to 158°F (
−
30 to 70°C)
Degree of protection
QFM81.2
IP 30 to EN 60 529
QFM81.21
IP 55 to EN 60 529
Safety class
II to EN 60 730
conformity to low-voltage directive
73 / 2 3 / EEC
UL
UL873
cUL
Canadian Standard C22.2 No. 24-93
Connection terminals for
20 AWG. minimum
2 × 16 AWG
maximum
Materials
Sensing element
Polymer
Casing with stem
PPS, Fortron 1140L6, fiberglass
reinforced
Cover
PC Lexan 940
Transparent cover
PC Makrolon 2014R, transparent
(only with QFM81.21)
Weight
Approximately 12 ounces (0.34 kg)
Maintenance
Maintenance-free, can be recalibrated
Wiring Diagram
SEN0510R1
1
2
3
1 – 2 Humidification
1 – 3 Dehumidification
Figure 3. Wiring Connections.