Armstrong AM-91A - Operation and Servicing

7
Putting the Humidifi er Into Operation
When Temperature Switch is Employed simply set hu-
midity controller at desired level, and turn on the steam.
When Temperature Switch Is Not Employed deactivate
operator control so that humidifi er control valve will remain
closed. Then:
A. Open steam supply valve, to bring humidifi er up
to temperature.
B. When drain line from humidifi er is at steam
temperature, activate the operator control.
C. Set desired relative humidity.
After the Humidifi er Is In Operation
Clean Strainer. The screen in the strainer installed in the
steam supply line should be cleaned a few days after the
humidifi er is placed in operation, and thereafter at least
once each season – more often if you fi nd much dirt in the
screen.
Check Trap. The steam trap is used to drain the humidi-
fi er should be inspected at the same time the strainer is
cleaned.
Trouble Shooting FSA, VSA
Humidifi er Will Not Discharge Steam
A. –Solenoid Fails to Open
1. Burned out coil.
2. Humidistat at fault.
3. Hand switch open.
4. Dirt in plunger tube or bent tube.
5. Steam pressure too high for unit as
furnished.
6. *Damaged piston ring.
7. *Plugged or restricted pilot orifi ce.
B. -Steam System Malfunction:
1. Silencing chamber plugged with dirt.
Remove and replace silencing material and
retainer.
2. Strainer screen plugged.
3. Dirt in steam line.
4. Steam valve closed in line to humidifi er.
5. Pressure reducing valve out of order.
*FSA-92 and FSA-93, VSA-92 and VSA-93 only.
Humidifi er Discharge Water
A. –Faulty Installation:
1. Long, untrapped supply line.
2. Humidifi er supply from bottom or side of
steam header.
3. Untrapped valve in vertical, downfeed
supply line.
B. –Faulty Drainage
1. Steam trap fi lled with dirt.
2. Return line pressure above humidifi er
pressure.
3. Too much vertical lift.
4. Wrong type of trap used.
5. Second trap short circuiting the
humidifi er trap.
Operation and Servicing
Humidifi er Discharges Continuously, Even though
Humidity Has Reached Desired Level:
A. –Mechanical Trouble:
1. Humidistat fails to open (points frozen).
2. Dirt holds solenoid plunger in open position.
3. Bent solenoid tube holds plunger in open
position.
4. Dirt between valve and seat.
5. Coil not de-energized.
6. Damaged spring.
7. Plugged bleed hole.
B. –Insuffi cient Capacity:
1. Not enough units to give desired relative
humidity.
Trouble Shooting AM, AMAF, AMEF
Humidifi er Will Not Discharge Steam
A. –Control System At Fault:
1. Faulty control valve operator.
2. Faulty humidity controller.
3. Faulty connections between humidity
controller and control valve operator.
4. Air valve closed.
B. –Steam System Malfunction:
1. Silencing chamber plugged with dirt.
Remove and replace silencing material and
retainer.
2. Strainer screen plugged.
3. Dirt in steam line.
4. Steam valve closed in line to humidifi er.
5. Pressure reducing valve out of order.
Humidifi er Discharges Water
A. –Faulty Steam Supply:
1. Long, untrapped supply line.
2. Humidifi er supply from bottom or side of
steam header.
3. Untrapped valve in vertical, down feed
supply line.
4. Boiler carryover.
B. –Faulty Operation:
1. Faulty temperature switch.
2. Humidity controller set up before humidifi er
has reached steam temperature.
C. –Faulty Operation:
1. Faulty temperature switch.
2. Humidity controller set up before humidifi er
has reached steam temperature.
Humidifi er Discharges Continuously Even Though
Humidity Has Reached Desired Level.
A. –Humidity Controller Out of Calibration.
B. –Trouble in Humidifi er:
1. Valve stem “frozen” to stem seal due to
unusual chemical or corrosive conditions in
steam system.
2. Operator spring broken.
3. Dirt or scale between valve and seat.