Two Compressors Joined Together

[GrumpyOne]

Hi There,
I have two commpressors that I would like to feed in to the same airline, can I just plumb them in to the one line and turn them on, or is there something else I need to do?
I have read the tutorial and the gent there has two compressors going in to the one line, which is what gave me the idea.
What about the power to run both of them, I read on here that 3.5hp is the max you could run off of a 220v supply. One of the compressors is a 2.5hp and the other is a 2.0hp, both with 13 amp fuses in the plugs but I do have a 32 amp socket I could plug them in to.

Any suggestions or advice.

 

[Screwdriver]

You would probably need to wire them both from the same pressure switch or only one of them will run to top up the tanks.

My only worry would be the amount of current draw when both motors try to start at the same time but if your supply is up to it, should be fine. Otherwise you'd have to faff about with some sort of delay switch to stagger them by a few seconds.

S.

 

[rtbcomp]

You would probably need to wire them both from the same pressure switch or only one of them will run to top up the tanks.

.................

No - each uses its own pressure switch. Set the pressures a few psi apart so they both don't switch on at the same time to avoid a heavy mains surge.

 

[brightspark]

Hi There,
I have two commpressors that I would like to feed in to the same airline, can I just plumb them in to the one line and turn them on, or is there something else I need to do?
I have read the tutorial and the gent there has two compressors going in to the one line, which is what gave me the idea.
What about the power to run both of them, I read on here that 3.5hp is the max you could run off of a 220v supply. One of the compressors is a 2.5hp and the other is a 2.0hp, both with 13 amp fuses in the plugs but I do have a 32 amp socket I could plug them in to.

Any suggestions or advice.

u said they have a 13 amp plug on each but u have a 30 amp socket and presumably fused at 30 amp back at supply .u cant just conect both in otherwise the fuse would be over rated for each comp .u could change your 30 amp plug for a double 13 amp socket and plug them both in to that

 

[Wendelspanswick]

Hi There,
I have two commpressors that I would like to feed in to the same airline, can I just plumb them in to the one line and turn them on, or is there something else I need to do?
I have read the tutorial and the gent there has two compressors going in to the one line, which is what gave me the idea.
What about the power to run both of them, I read on here that 3.5hp is the max you could run off of a 220v supply. One of the compressors is a 2.5hp and the other is a 2.0hp, both with 13 amp fuses in the plugs but I do have a 32 amp socket I could plug them in to.

Any suggestions or advice.

As rbtcomp said, if the trip keeps knocking out you might have to move one compressor onto a separate circuit if you can.

 

[Screwdriver]

No - each uses its own pressure switch. Set the pressures a few psi apart so they both don't switch on at the same time to avoid a heavy mains surge.

ORLY?

When does the second pressure switch turn on I wonder?

S.

 

[Rig Pig]

Once the receiver pressure drops the second unit will pick up the load.

 

[Maker]

ORLY?

When does the second pressure switch turn on I wonder?

S.

When the pressure gets really low, the second one will kick in.

 

[rtbcomp]

ORLY?

When does the second pressure switch turn on I wonder?

S.

Assuming the 1st compressor is set to the lower pressure and the hysteresis is the same for both:

Once the 1st compressor reaches it's pressure it switches off
The 2nd compressor will continue to fill both tanks **
When the 2nd compressor reaches it's pressure it switches off
The pressure drops in both tanks
The 2nd compressor will switch on when it's "turn on" pressure is reached
The pressure continues to drop in both tanks
The 1st compressor will switch on when it's "turn on" pressure is reached

And so the cycle repeats.

** Assuming the tanks are connected directly without a non-return valve.

 

[Farside]

Assuming the 1st compressor is set to the lower pressure and the hysteresis is the same for both:

Once the 1st compressor reaches it's pressure it switches off
The 2nd compressor will continue to fill both tanks **
When the 2nd compressor reaches it's pressure it switches off
The pressure drops in both tanks
The 2nd compressor will switch on when it's "turn on" pressure is reached
The pressure continues to drop in both tanks
The 1st compressor will switch on when it's "turn on" pressure is reached

And so the cycle repeats.

** Assuming the tanks are connected directly without a non-return valve.

And the 2nd compressor will just top up both tanks, so the 1st compressor never switches on again - is the way I see that.

 

[Screwdriver]

Assuming the 1st compressor is set to the lower pressure and the hysteresis is the same for both:

Once the 1st compressor reaches it's pressure it switches off
The 2nd compressor will continue to fill both tanks **
When the 2nd compressor reaches it's pressure it switches off
The pressure drops in both tanks
The 2nd compressor will switch on when it's "turn on" pressure is reached
The pressure continues to drop in both tanks
The 1st compressor will switch on when it's "turn on" pressure is reached

And so the cycle repeats.

** Assuming the tanks are connected directly without a non-return valve.

Now put some numbers in and tell me when the compressor with the lower set pressure switch will ever activate...

Or are you going to rely on the pressure continuing to drop after the first compressor kicks in?

 

[rtbcomp]

Or are you going to rely on the pressure continuing to drop after the first compressor kicks in?

Yes - otherwise why connect 2 compressors if one will do the job?

And the 2nd compressor will just top up both tanks, so the 1st compressor never switches on again - is the way I see that.

It will switch on if the demand is greater than one compressor can supply by itself.

 

[Rig Pig]

This is the way all the big industrial sets are hooked up, a lead unit and a lag unit, during peak demand periods both units run, as the demand drops the lag unit shuts down to reduce cost and wear and tear.

 

[premmington]

This is the way all the big industrial sets are hooked up, a lead unit and a lag unit, during peak demand periods both units run, as the demand drops the lag unit shuts down to reduce cost and wear and tear.

Yes...

Correct terms used. Lead and Lag (also heard it described as master and slave)

 

[brightspark]

i have a twin unit both pumps run up to about 130 psi and cut out .when in use the pressure drops to 95 psi and 1 pump cuts back in. if a lot of air is being used and drops below 95 psi the second cuts back in at 90 psi and both are running .if im blasting with them i run it up to just below cutout pressure and start using the air so both are still running and will only cutout if the pot ist using all the air

 

[Farside]

Yes - otherwise why connect 2 compressors if one will do the job?



It will switch on if the demand is greater than one compressor can supply by itself.

I see what you mean now - so the primary would be the larger of the two, in this case. The smaller (and presumably lighter-duty) unit only coming in when needed at times of high demand.
Which is bloody useful to know - it means I can go out and buy another unit of whatever size I happen across (within reason). If it's larger than what I've got, it can be the primary (lead) and if same size or smaller can be the secondary (lag).
When I start doing some blasting I see I'll need more capacity, but was reluctant to lay out large money on bigger kit.

 

[rtbcomp]

Not heard "lead & lag" before, describes the situation perfectly.

I see what you mean now - so the primary would be the larger of the two, in this case. The smaller (and presumably lighter-duty) unit only coming in when needed at times of high demand.

It can either way round - lead & lag are determined by the pressure switch settings.

I have a big noisy compressor in the yard and a smaller one inside. So as not to annoy the neighbours (too much) I have the bigger outside unit set up as the lag machine.

The biggest reason for having lead & lag is to avoid the mains surge you'd get if both machines switched on at once (as described above)

 

[premmington]

I have two compressors on one ring main! I have the little Hydrovane 11 cut in first, then on high demand the big Ingesoll Rand cuts in.

Reason being the Hydrovane produces less air but far less noise!

 

[Bill Edwards]

It's probably quite a good way of getting more output from a supply that one big unit as they will be staggered slightly and it's start-up that causes issue.
Replace the 32a socket with a double so each compressor has it's own 13a fuse.

I would typically aim to have both compressors set to go on and off at the same pressures.
You don't actually want them to both kick in at the same moment, but in practice no amount of fine tuning is going to make them come on at the exact same second.
They'll then just run nicely together. The only thing you need to make sure is that the pressures are OK - if you have one compressor that's only supposed to go up to 120 psi and the other to 150, make sure you drop the 150 down to 120 otherwise, at best, that one will do most of the work and at worst it'll be too much pressure for the other one.

 

[dannyp]

you just plum both compreesor up together and tuen them on, and it'll just work as allready stated.

you'll end up with a master / slave arrangement. one will allways fire up first if your only useing a littel air the one compressor will handel it all, if your useing lots and pressure continues to fall the 2nd will fireup. also as said this is quite usefull.