Page 104 - Improving Machinery Reliability
P. 104
76 Improving Machineiy Reliability
Buffer gas IN
Figure 2-14. Gas-lubricated mechanical seal (double seal). (Courtesy of Burgmann
Seals America, Houston, Texas.)
margin between NPSHA and NPSHR. These findings have prompted many users to
develop and use tentative guidelines that are largely empirical in nature.14 The publi-
cation of quantitative correlations of suction recirculation as a function of proximity
to best-efficiency-point (BEP) flow for pumps with different construction and perfor-
mance characteristics had to wait until late 1981. Details are given in Chapter 3.
Bid Tabulation and Bid Conditioning: An Overview
Bid tabulations represent the culmination of the engineer's specification efforts.
Proposals are submitted by the various vendors and pertinent items are written up
side by side to facilitate easy comparison. To the experienced engineer, the bid tabu-
