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Let’s take it apart

Edwards E2M-1.5 Post-Rebuild Run

February13

E2M1.5 ThumbnailIn the interest of full disclosure, it has been months since I got the E2M-1.5 running. The first thing I did was hook it up to the SMC Digital Pressure Switch to see how much vacuum I had.

This is the last in a series of entries about the Edwards E2M-1.5 vacuum pump I acquired on eBay.

Part 1: Disassembly | Part 2: Pump Rebuild | Part 3: Motor Repair

The gauge I’m using, by default, reads in kilopascals (kPa) referenced to atmospheric pressure.  Normal atmospheric pressure is accepted to be 101.3 kPa. This is, of course, something of a moving target since atmospheric pressure changes with the density of the air mass over your head. As atmospheric pressure changes, the reference point for the gauge changes.

Vacuum switch pressure

The pump appears to be pulling pretty good vacuum. If we assume that atmospheric pressure is 101.3 kPa, then the absolute pressure is 0.7kPa or about 0.53 mmHg. The pump should be able to pull down to 0.005 mmHg.

The problem with measuring such low vacuum is that a gauge capable of indicating that last millimeter of mercury between 1 mmHg and 0 costs several hundred dollars. While it may be a strange source of  pride, in the end, I really don’t care.

What I do care about is being able to pull enough vacuum to boil water at room temperature.  That I can do.

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