Replacing The Relay; Replacing The Case And Cover - Fisher 4194B Series Instruction Manual

W3440 / IL
W3492 / IL
Figure 5-1. Changing the Scale
5. Secure the scale with the four self-tapping screws
(key 37).
6. If the controller has remote set point (suffix letter
M), perform the appropriate remote set point zero and
span calibration procedure in section 3 or 4.
7. Perform the appropriate process indicator zero and
span calibration and the flapper alignment procedures
in section 3 or 4.

Replacing the Relay

1. Loosen the two captive screws that hold the relay
(key 50) in place.
2. Tip the relay slightly toward the side of the case to
clear the output pressure gauge (key 46) and lift out
the relay.
3. Make sure the replacement relay has three O-rings
(keys 13 and 15) installed as shown in figure 5-2. The
fourth port is for exhaust and does not require an O-
ring.
4. Install the replacement relay, making sure the tab
on the relay, shown in figure 5-2, aligns with the tab on
the frame.
5. Tighten the two screws that hold the relay in place.
4194A, B, and C Series
CLEAN-OUT
WIRE
RELAY
TAB
W5744 / IL
Figure 5-2. Relay Construction
6. Perform the appropriate Flapper Alignment proce-
dure in section 3 or 4.

Replacing the Case and Cover

CAUTION
The case and cover are an integral unit;
attempting to separate them will damage
the hinge. If the cover needs to be re-
placed, replace the case also.
1. Remove the external piping and fittings from the
controller.
2. Remove the controller from its mounting to a main-
tenance area.
3. Remove the nine screws (key 38) from the case
and cover assembly (key 1) and lift out the controller
assembly. If the controller has remote set point (suffix
letter M), use a screwdriver or appropiate tool to de-
flect the case slightly at the remote set point connec-
tion to remove the controller assembly. Inspect the
O-rings around the external piping connections and
replace as necessary.
4. Position the controller assembly in the replacement
case and cover.
5. Start the nine mounting screws, but do not tighten.
6. Slide the controller assembly down to assure an
O-ring seal at the pressure connections along the bot-
tom of the case. Hold the controller assembly in place
while tightening the nine mounting screws.
7. Remove the blow-out plug (key 72) from the origi-
nal case, and install it in the replacement case.
EXHAUST PORT
(NO O-RING
USED)
O-RINGS
RELAY
MOUNTING
SCREWS
5–5