Page 157 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Reciprocating and Liquid Ring kcuum Pumps 139

Flgure 3-14. Cross section view of two-stege vacuum pump.

In “sandwich” construction machines such as in Figure 3-14, the cor-
rect clearances are more difficult to obtain. A two-stage machine with
thrust end at the left is shown, Several measurements are required to en-
sure correct assembly (refer to Figures 3-13 and 3-14).

1. The length of the center bodies “A” and “B” (items 4, 7).
2. The length of the impeller hubs “C” and “D” (items 3, 9).
3. Check that the impeller ends are parallel and the tips .03 to .08 mm
(.001 to .003 in.) narrower than the hubs.
4. The depths of the recesses at the impeller hubs “E,” “F,” “G,” and
“H.”
5. Check that the surfaces of the intermediate plates (items 5, 6) are
parallel and flat within .04 mm (.0015 in.) and record their thick-
ness at the outer circumference “I,” and “J.”