2-1/2" Oil Filled Vacuum Pressure Gauge - Stainless Steel Case, Brass, 1/4" NPT, Lower Mount Connection, 30HG/0

I have gone through a ton of cheap gauges over the years. As a plumber I need to test water pressure at my client's homes a few times a day. Most gauges fail at this task within a few weeks or months. A quick hit will leave many gauges sitting at 10-20 PSI all of a sudden and you just can't trust that adding that amount will give you an accurate read. Hard to show a customer that their pressure is high when the gauge starts at 20 PSI too. The oil acts as a shock absorber and prevents this damage from happening. It also prevents the gauge from freezing when a little water is left in it and it spends the night in a cold truck. The dial is of a nice quality and it has a solid feel to it. Been carrying this one with me for about a year now and it is good as the day I bought it. Thing takes some abuse too because I have it in my pocket a lot of the time and either lay or sit on it quite a bit.UPDATE - So after about a year, the gauge started to climb on its own. Noticed it sitting at 40, then 60, and eventually it was hanging out at 100 PSI. Not sure if water maybe water was still able to freeze inside it or not, because it started when the weather got colder. Seemed to make it through last winter just fine so not sure what happened. One day I used it and the next day it was no longer at 0 PSI and it had simply sat in my truck overnight. Still, it lasted about a year under pretty tough conditions which is far longer than any other gauge I used for the same purpose.

This gauge far exceeded my expectations. Strong construction, very attractive, and the 2.5" dial face makes a huge difference in ease of readability vs. the 2" gauge that I've replaced with this one. Seems to have leaked a few drops of glycerin in transit but IMO that's to be expected and I have no problem with that. The glycerin level is great, air bubble couldn't have been more than a ml or two and after tipping the gauge to allow the bubble to float up behind the dial plate, it stays there. No obstruction of the large easy to read gauge dial at all. Even if it were to have arrived too low, it's very simple to pop off the rubber plug to top it up. This is NOT the type where you have to permanently cut the plug open to vent and zero the gauge, leaving it forever open to leak everywhere if tipped; it comes with a brass pin that you pull up to vent before/during use and push back in to keep it from leaking during transport. Despite arriving with a bit of glycerin leakage in the package, it doesn't seem to leak at all with the pin engaged even if stored upside down overnight. Perfect if you want a glycerin-damped gauge for a portable/non-permanent application. Probably about as accurate as you'll ever need if you're using an analog bourdon tube vacuum gauge to begin with.

Easily fit in to the water pump! Seems to work accurately , so far so good!! One month later.

I fully disagree with the first reviewer. I purchased this pressure gauge as a race car tire pressure gauge. I don't like spending hundreds of dollars on pressure gauges that are sold as racing tire pressure gauges. A pressure gauge is a pressure gauge. I just need them durable and accurate. This one is. I have used it all year, beat the hell out of it, and it is still the most accurate pressure gauge I have ever even seen. My racing friends envy me. I tell them how much I paid for it, and they balk. This shows how little people know about pressure gauges. I also like the white face. It is easy to read when airing up trailer tires in the dark.I have two of these gauges because I made a mistake by following directions. Let me back up, I don't know why this gauge is liquid filled. It's nice, but I really don't know what the liquid solves. When I got the first one, I cut the rubber seal like the directions say. but then it started leaking fluid. I supposed it is meant to be mounted permanently somewhere. I resealed the hole with silicone, but I bought another gauge because I like it so much. I use the first one for air conditioning charging, where it works perfectly.Regardless of the designed purpose of this gauge, it works perfectly as a heavy-duty tire pressure gauge and an air conditioning recharging gauge (for refrigerants including R12, R134, and propane).

This gauge is about the least expensive that you'll find out there that's liquid filled, and it's great for low pressure leak testing of sealed systems (and other uses, but this is what I'm using it for). For the money, it is significantly better than most, if not all, non-liquid filled gauges, most of which tend to stick. After running a gas leak test at say 10 psi for a while, many cheap gauges won't indicate a reduction in pressure right away as you bleed off pressure... they'll hang for a bit and then suddenly jump down a few PSI. This means that during the test, you need to "flick" them a few times periodically to overcome their getting stuck to discover whether or not any pressure has leaked. This gauge operates very smoothly, no "flicking" required. Bleed off 1/10 psi and you'll see the gauge drop a smidge.The only reason for a 4 star rating vs 5 is that after running a 24 hour test at 9 psi, I discovered what I believe was a slight amount of pressure that leaked though the gauge. Prior to the test, I removed any internal pressure in the gauge by pulling the little "valve" in the top of the gauge... but after the test, which indicated a few tenths of a psi pressure drop, there was pressure built up in the gauge again. Outside temperature was virtually identical at the start and end of the test, so it appears this slight pressure drop was not a system leak, but in fact was leaked thru the gauge. I ran another 24 hour test using a different gauge, and there was no pressure drop after 24 hours.The bottom line on at least this one specific gauge: it's a great gauge for shorter duration tests where a microscopic leak thru the gauge won't have any measurable affect; but for a longer term test, you can expect a small pressure drop.