Overview
Vacuum gauge, 2.5 inch dial, 0–30 inHg dual scale, supplied with the PGUC-250 mount. Sapphire part number 26-044, OEM code 106840. It replaces 26-004.
It is an alternate for HydraMaster 074-017 and 074-025, which makes it one of the more useful cross-brand parts in the catalogue.
Why the vacuum gauge is the most under-used instrument on a truckmount
Most operators watch pressure and temperature and ignore vacuum, which is the wrong way round — the vacuum gauge is the one that tells you when the machine is losing performance for a reason you can fix.
What the readings mean, once you know your machine's normal:
- High vacuum, poor recovery at the wand — a restriction. Blocked filter bag, blocked in-tank filter, a crushed or kinked hose, or a plugged wand slot. The machine is pulling hard against something.
- Low vacuum, poor recovery — a leak. Recovery tank lid gasket, a split hose, a loose cuff, or a lid not latched. Air is getting in where it should not.
- Vacuum falling away over a job — usually a bag loading up.
Those two symptoms feel identical at the wand and have opposite causes. Without a gauge you are guessing; with one you know which half of the system to look at.
Establish your baseline
The number that matters is your machine's normal, not a figure from a manual. Note the reading with a clean bag, a good lid seal and the hose you normally run, when the machine is known good. Everything after that is a comparison against it.
Fitting
Supplied with the PGUC-250 mount. Check your panel cut-out and the existing mounting arrangement before ordering if you are replacing a gauge that was fitted differently.
A gauge whose needle no longer returns to zero at rest has been shocked or over-ranged. Replace it — a gauge you do not trust is worse than none, because it sends you looking in the wrong place.
Frequently asked questions
Will it suit a HydraMaster?
It is listed as an alternate for HydraMaster 074-017 and 074-025. Check the mounting on your machine, and ask us if you are unsure.
What does it replace?
Sapphire 26-004.
Is the mount included?
Yes — the PGUC-250 mount is included.
What is a "dual scale" gauge?
It carries two units on the one dial. Read whichever your procedure uses, and stay consistent so your readings remain comparable.
Chasing a vacuum problem? Tell us what the gauge reads at rest and at the wand and we will help you work out whether you are looking for a leak or a restriction.
