Instruction Manual
D200158X012
4194S Controllers
July 2018
26
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
replaced, replace the case also.
1. Remove the supply and output piping from the controller. Bleed away any process pressure, and carefully remove
the process pressure piping from the controller.
2. Remove the controller from its mounting (see the Installation section) to a maintenance area.
3. Remove the nine screws (key 38) from the case (key 1) and lift out the controller assembly.
4. Install the controller assembly in the replacement case.
5. Slide the controller frame down to assure an O‐ring seal at the pressure connections. Hole the frame in place.
6. Install and tighten the nine mounting screws.
7. Remove the blow‐out plug (key 72) from the original case, and install in the replacement case.
8. Mount the controller as described in the Installation section.
9. Connect the supply, output, and process pressure piping to the controller.
Gauges
CAUTION
Before performing this procedure, be sure the replacement gauges are the correct range so that the gauges are not
damaged by overpressure.
1. Unscrew the output gauge (key 46) or the supply gauge (key 47) from the frame (key 3).
2. Before installing the replacement gauge, coat the threads on the gauge with a suitable sealant.
3. Screw the replacement gauge into the frame.
Pressure Control Block
1. Carefully remove the process pressure piping from the controller after bleeding away process pressure.
2. Loosen the nut on that portion of the tubing that connects the pressure sensing element to the pressure control
block (key 57).
3. Remove the two cap screws (key 58) that hold the pressure control block to the frame (key 3), and lift out the
pressure control block.
4. Install the O‐ring (key 7) on the replacement pressure control block.
5. Install the replacement pressure control block to the frame with two screws (key 58).
6. Tighten the nut that was loosened in step 2.
7. Apply the process pressure equal to the maximum value on the process scale, and check for leaks.
8. Connect the process pressure piping to the controller.