Compressor questions

[Gary WoodingParticipant @garywooding25363]

This is really a follow-on to my thread **HERE**

I ended up buying the Hyundai 50L recommended by Anthony. It's noticeably superior to the one its replacing, and has two components that simply didn't exist on the old one. And I don't know what they are or what they are for. Can anyone help please?

Here's an annotated picture of the new machine.

Here is Item 1.

Here is Item 2, which is a close-up of the top of Item 1.

And here is Item 3. What is it and how is it used?

[Gary WoodingParticipant @garywooding25363]

[Speedy Builder5Participant @speedybuilder5]

Item 3 – automatic water drain. Drains at low pressure ie: startup. You should also be able to press the bottom brass fitting up to release trapped water whilst under pressure

Items 2 and 1 – Pressure relief valves. These are open to atmosphere on startup of the motors and reduce the load on the motors until they have spun up to speed. It is possible that if they didn't work, that the motor would stall on startup and possibly burn out. It looks like they are adjustable – perhaps for the time delay, but just guessing on that bit.

Although not mentioned, Item 3, the pressure regulator/ condensation filter also has the safety pressure release valve (brass fitting at the side).

[SamsarandaParticipant @samsaranda]

Name says super silent, how silent is that? Items 1 and 2 appear to be pressure regulating valves of some kind. Item 3 looks like an oil and water trap. Dave W

[Martin KyteParticipant @martinkyte99762]

Looks to me like a pressure switch to turn the motors off when max pressure has been reached and item 3 would be a water trap. There is a drain at the bottom of th sight glass for when it gets near full,

Nice compressor, good for spraying.

regards Martin

[Dave HalfordParticipant @davehalford22513]

1 & 2 looks like an electric unloader valve, older machines have a mechanical version which probably wastes power. it should blow off air which empties the braided hoses when the motor stops to prevent restarting under pressure.

3 filter regulator they are either auto and empty themselves or manual which means you pop it up whenever you see liquid in there. The black knob on top reduces pressure delivered to the hose connector. Don't mess with insides of the black box with the yellow sticker on it, thats the pressure switch as well as the start – stop

[noel shelleyParticipant @noelshelley55608]

Item 1 and 2 The electric unit will be an unloader valve , the brass lump is a non return. Item 3 is the pressure control valve water trap and adjusterble regulator. The two gauges tell you tank pressure on the left and reduced pressure on the right. To adjust you often have to pull the black knob up to turn and push down to lock. Noel.

[Speedy Builder5Participant @speedybuilder5]

And, don't forget to drain the water from the tank by a drain valve which should be underneath the tank somewhere.

[Gary WoodingParticipant @garywooding25363]

Posted by Samsaranda on 07/03/2021 11:40:12:

Name says super silent, how silent is that? Items 1 and 2 appear to be pressure regulating valves of some kind. Item 3 looks like an oil and water trap. Dave W

It's definitely not silent, but it's a great deal less noisy compared to the one it replaced. It was almost impossible to talk when the old one was running, but there's no problem with this one. It's a great improvement, I'm rather pleased with it.

[Gary WoodingParticipant @garywooding25363]

Thanks for the super answers to my questions, but I have another one. The (rather skimpy) manual contains the following sentence – "release the air in the tank by pulling the safety valve". The only part that could be a safety valve is the brass object to the left of the pressure gauge, but there's nothing to pull. There are two flats on the protrusion, and it can be rotated by use of a spanner, but nothing happens when I rotate it about 90 degrees, and I'm unhappy about turning it more when I don't know what should happen.

[Dave HalfordParticipant @davehalford22513]

There used to be a 'key ring' through the centre bit back in the day and regardless of what the instructions say leave the safety valve alone. You have to pull them the same amount as 110psi+ pushes them to open the valve, then you get a100psi jet blowing at your hand which is not comfortable. Twisting it will just knacker the seal and the thing will continually leak.

[noel shelleyParticipant @noelshelley55608]

As dave has said DO NOT try to turn this ! The two flats may be the air out let and the valve may be destroyed or damaged beyond repair. It always a good plan to easy the valve from time to time to check it will lift. I came across one where the spring had gone solid and would not open. Easing it would have shown up this fault, or have prevented it.. Be careful of screwing BSPT or any taper fitting into aluminium housings, use PTFE tape and tighten only enough to seal or you may split the alli. Noel

[Gary WoodingParticipant @garywooding25363]

Thanks Dave and Noel, I'll leave it alone.

[Anthony KendallParticipant @anthonykendall53479]

Posted by Dave Halford on 07/03/2021 18:07:34:

There used to be a 'key ring' through the centre bit back in the day and regardless of what the instructions say leave the safety valve alone. You have to pull them the same amount as 110psi+ pushes them to open the valve, then you get a100psi jet blowing at your hand which is not comfortable. Twisting it will just knacker the seal and the thing will continually leak.

At least two of the suppliers are saying the key ring on the safety valve is against EU regulations and are supplying the same compressor without the key ring! Good advice from Dave.

The Hyundai is not silent, just pretty quiet. A 50L direct-driven compressor is quoted at 97dB.
I had a Wolf belt-driven 50L and its sound level was quoted 80db.
The Hyundai is quoted 60dB.
The sound level halves every 6dB going down, so the Hyundai is as Gary says, acceptably quiet. Just one caveat, the others have 14 CFM output and the Hyundai is 11.5, but, for me, it's worth it.

You can go down to 40dB with the Bambi BB50D, but it costs nearly double and gives only 3.5CFM – but it may suit your needs!

[Adrian R2Participant @adrianr2]

I'd love to know what the legal defintion of "silent" is….guessing it has as much meaning as "quality" or "high performance".

[OldironParticipant @oldiron]

Best to let the air bleed out from the vavle under the tank so as to drain any water accumalation.

regards

[Gary WoodingParticipant @garywooding25363]

I also have a little HydroVane compressor that I got for a song. I use it for blowing swarf, its too small for much else – except airbrushing. But it is certainly very quiet – little more than a gentle purring.

[noel shelleyParticipant @noelshelley55608]

I have one, almost what most of us would silent. Keep it ful of oil and it will last for ever. Built for paintspraying. Noel.

[Howard LewisParticipant @howardlewis46836]

The advice given when my compressor came from the local compressed air specialists was to open the drain after every use, and to leave it open until next needed.

In this way, any condensation on the walls of the receiver can coalesce and run down to the exit via the open drain. Moist air can exit by the same route.

Howard

[Gary WoodingParticipant @garywooding25363]

Posted by noel shelley on 08/03/2021 13:19:52:

I have one, almost what most of us would silent. Keep it ful of oil and it will last for ever. Built for paintspraying. Noel.

Noel, do you have a user manual for it? I've had no luck at all from searching the internet. I'm guessing that 'A' in the photo is the oil filler cap, but don't know what 'B' and 'C' are.

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