Maintenance Manual
P13631: Process Control Gravity Fed
2013-12-10
Table of Contents
Component Specific Maintenance ................................................................................................................ 2
Level Transmitter .......................................................................................................................................... 2
Reservoir Assembly ....................................................................................................................................... 3
Pneumatic Circuitry....................................................................................................................................... 4
Worn Tube Ends ............................................................................................................................................ 4
Leaks at Threads ........................................................................................................................................... 4
Lubricator ...................................................................................................................................................... 5
Hydraulic Circuitry......................................................................................................................................... 6
Leaks at Tube Fittings.................................................................................................................................... 6
Leaks at Tri-Clamp Fittings ............................................................................................................................ 7
Leaks at Threads ........................................................................................................................................... 7
Mechanical Maintenance.............................................................................................................................. 9
Loosening Fasteners ..................................................................................................................................... 9
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1. Component Specific Maintenance
1.1 Level Transmitter
The level transmitter is a particularly finicky item. Its circuitry is very sensitive to physical disturbances
and therefore, care must be taken when handling this item. When mounting the level transmitter to the
frame for use with the apparatus, carefully place a small strip of double sided table at the top rear of the
transmitter and adhere it to the frame.
At the front top of the transmitter is a hydrophobic membrane filter. Check the filter for wear. If the
transmitter shows signs of excessive wear, bends or breaks, it may be necessary to replace the
transmitter altogether.
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1.2 Reservoir Assembly
At the time of construction, stainless steel tubes were welded to the reservoir as part of the design. The
filler material for the welds may not have been a stainless material and/or could have contained
contaminants susceptible to oxidization. Periodically check the weld joints for oxidization. If there is any
indication of such, disconnect the reservoir assembly from the apparatus. Remove oxidization with
Scotch-Brite or other abrasive. Wipe off thoroughly, rinse, and reattach to the apparatus.
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2. Pneumatic Circuitry
2.1 Worn tube ends
Much of the pneumatic circuitry utilizes push-to-connect fittings for ease of assembly and disassembly.
As a consequence of repeated assembly and disassembly, the outer diameter of the pneumatic tubing
may become worn at the fitting interface. If a leak occurs at this point, check to see if there is sufficient
slack in the length of the tube to cut 1/4" of length off the end. Perform this repair if allowable. If there
is not sufficient length, replace the tubing.
2.2 Leaks at threads
The push-to-connect fittings come pre-wrapped in a sealant. Over time this may become worn, causing
a leak at the threads. To fix this, wrap 1-2 layers of Teflon tape over the treads and reconnect to
associated components.
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For the manifold assembly, all components were sealed with red loctite. If leaking occurs, unmount the
manifold from the apparatus. First attempt to seal the leak with more loctite. If this doesn't work, apply
heat to the joint with a torch and break the thread sealant with a mallet and wrench. Clean the threads
off and apply a fresh layer of loctite making sure to get a full circumference of application. Reassemble
and allow 24 hours minimum to cure. Remount the manifold the apparatus.
2.3 Lubricator
The nitrogen supply in the chemical engineering laboratories at RIT should be lubricated out of the
outlets available. If the amount of lubrication is insufficient and pneumatic components start to show
wear or poor actuation performance, install a lubricator onto the assembly and attach in series
upstream the existing circuitry.
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3. Hydraulic Circuitry
3.1 Leaks at tube fittings
During the course of normal apparatus usage, leaks may form at the joints of the tube fittings. These
fittings are used with steel tubing as well as various plastic tubings. First assure that the ferrules are
properly installed and oriented. They should make a water tight seal around the tube which the fitting
connects to. At this point tighten the nut down until very tight. If the fitting still leaks, it may be
necessary to replace the tube and/or fitting.
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3.2 Leaks at Tri-Clamp fittings
If a leak occurs at one of the Tri-Clamp fittings, disassemble the clamp and remove the fittings from one
another. Inspect the gasket between the two fittings. The gasket should be free of any abrasion, nicks,
cuts, gouges, etc.. Replace if necessary. Reconnect the fittings by assuring properly alignment with the
fitting. If this is so, the joining fittings should be concentric. Reattach the Tri-Clamp fitting.
3.3 Leaks at threads
Some of the fittings in the hydraulic circuit create a seal via their threads. Such a case are the fittings
which connect the control valves to the 3/8" tubing. If a leak occurs at a threaded fitting, remove that
fitting from the apparatus. Remove any Teflon tape if necessary. Inspect the threads for any damage. If
the threads have any significant damage, they may not be creating a seal and causing the apparatus to
leak. If the threads are damaged, replace the fitting.
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If the threads are not damaged, wrap the threads with fresh layers of Teflon tape starting at the first
thread. Once thoroughly covered, reassemble. Tighten until very snug. If the threads still leak after this
point, replace the fitting.
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4. Mechanical Maintenance
4.1 Loosening fasteners
During normal use and transport of the apparatus, some fasteners may become loose. Most fasteners
feature a lock washer to prevent this scenario, but sometimes it happens. Periodically check all the
fasteners for snugness. No components fastened to the assembly should be free to translate. Check the
fasteners on the table, table braces, top and bottom shelf frames, wheels, and various components fixed
to the frames.
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