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10
Level
Installation, operation & maintenance instructions
IP152, Rev A
D
April 2012
Maintenance of the Mobrey vertical level controls
Inspection and maintenance shall be carried out by suitably trained personnel in accordance with applicable codes of
practice.
Series B-Vertical Integral Type
This type of control is of the ‘sealed chamber’ type and the float or displacer mechanism cannot be removed.
However, the switch mechanisms and switch head should be visually checked periodically.
1. Isolate electrical circuits to control and disconnect wiring as necessary.
2. Remove the switch head cover and examine the switch mechanism body for any damage. Ensure that wiring is in good
order and that all the screws are tight. Dismantling of switch unit is not recommended and replacement of the
complete switch unit will be found to offer the quickest and most economical solution in event of faulty operation.
See page 10.
3. Check sealing gasket / “O” ring and replace if necessary.
4. Check the cover seals are present and in good condition, and then replace the cover.
(i) Before energizing flameproof / Type ★7★ models, ensure the cover locking safety grub screw is replaced and
tightened. Do not energize if the cover locking safety grub screw is missing.
(ii) Before energizing weatherproof / Type ★4★ models, ensure the weatherproofing fibre sealing washer at the crown nut
is in place.
Series X - Vertical Flanged Type
This type of control is flanged between the switch head and chamber such that the float may be withdrawn and removed from
the chamber for inspection.
1. Isolate electrical circuits to control and disconnect wiring as necessary.
2. Isolate the chamber from the pressure vessel by closing the isolation valves, and open the valve of the drain connection.
3. Remove nuts holding control to chamber, carefully withdraw switch head and float assembly, taking care not to bend the
float rod.
4. Separate float assembly from switch head by removing stop clip.
5. Inspect the chamber and remove any deposits.
6. Check float, float rod and magnet for excessive wear, clean and replace as necessary.
7. Fit replacement joint and reassemble, taking care not to bend the float rod. Firmly tighten nuts on top flange, using bolt
torque values given in tables on page 12.
8. Remove the switch head cover and examine the switch mechanism body for any damage. Ensure that wiring is in good
order and that all the screws are tight. Dismantling of switch units is not recommended and replacement of the
complete switch unit will be found to offer the quickest and most economical solution in event of faulty operation.
See page 10.
9. Check sealing gaskets / “O” ring and replace of necessary.
10. Check the cover seals are present and in good condition, and then replace the cover.
(i) Before energizing flameproof / Type ★7★ models, ensure the cover locking safety grub screw is replaced and
tightened. Do not energize if the cover locking safety grub screw is missing.
(ii) Before energizing weatherproof / Type ★4★ models, ensure the weatherproofing fibre sealing washer at the crown nut
is in place.
11. Close drain valve connection, open isolating valves and check that the control is operating at the correct levels.
Series D - Direct Mounted Type
This type of control is mounted directly onto the process vessel, or may be mounted in a chamber.
1. Isolate electrical circuits to control and disconnect wiring as necessary.
2. Ensure the vessel is vented to atmosphere, or isolate any chamber from the vessel by closing the isolating valves, and open
the valve of the drain connection.
3. Remove nuts holding control to chamber or vessel. Carefully withdraw switch head and float assembly, taking care not to
bend the float rod.
4. Separate float assembly from switch head by removing stop clip.