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SECTION 5
CLEANING AND MAINTENANCE
Standard laboratory procedures apply to the cleaning of the Differential Sticking Tester. After each test,
the cell should be dis-assembled completely and thoroughly cleaned and dried of all sample and other
contaminants, with particular attention to "O" rings and "O" ring grooves.
Wash and dry the support screen and locking mesh disc.
Wipe spilled sample or other debris from the stand. Some sample materials may damage the finish of
these parts if allowed to remain on them for a long period of time.
A.
Cell Maintenance
1.
Cell Corrosion
CAUTION
CORROSION PITTING AND CRACKING CAN CAUSE RUPTURE OF CELLS
Sample fluids used in this instrument can, at times, cause corrosion of the test cell and cell
cap. The standard cell is made of Type 303 Stainless Steel. Cells are available in other
materials for use where the stainless steel is not suitable because of corrosion problems. An
inspection of the inside of the cell for evidence of corrosion should be made periodically. Light
corrosion may be removed using 320 or finer wet or dry sand paper. Deeper corrosion pitting
may be removed by sand blasting the area of the corrosion. More severe corrosion will
require re-machining or re-surfacing the inside of the cell. If severe corrosion is evident, the
cell should be replaced.
2.
"O" Rings
Inspect all "O" rings as they are being cleaned for cuts or nicks. Replace any damaged "O"
rings. Lubricate "O" rings before they are installed. For most applications, laboratory stop
cock grease is satisfactory; however, since some "O" rings come into contact with the sample,
care should be taken that the lubricant is compatible with the sample.
3.
Valve Stems
A metal to metal pressure tight seal is made between the valve stem and its seat. Leaks can
occur if either the valve stem or seat is damaged. The cone point of the valve stem may be
inspected for damage by removing the valve stem from the cap or body. If the point is
damaged, replace the valve stem. If the point appears to be in good condition, the seat in the
cell or cap may be rough. A 5/16 inch drill bit can be used to resurface the seat, or a special
tool (38717) may be used. Valve stems should be inspected for possible plugging of the
passages by dried sample. A small drill or wire can be used to insure that both the cross bore
and the main passage openings are clear.