Correct Piping Size Needed

a compressor that supplied 1 bar or 14.5 psi through a 1 5/8 tube.

How far above sea level are you that you need a compressor to generate atmospheric pressure?

He does not state "absolute", so the convention is to assume gauge, but then you had guessed that anyway.

One of these days Alice! Pow! Right too the moon Alice right too the moon!

This is a good riddle into the unknown. To be more to the point:/// Hints:

1. check what regulator was on the old compressor

2. Check your old compressor on power and capacity.

3. Check how much air you need to feed your loads.

I suggest the given values are Gauge (gage) values, overpressure? Not derived from the barometer?

Hypothesis A.

The big pipe is needed for the cfm: According to your pipe, if 1"5/8 I should play it safe and get a pressure regulator of that size or bigger.

Check for which one available that fills in on your precision needs. ( fluctuations tolerance - caused by hysteresis)

The more membrane diameter, the more precise but also the more costly.

See also that your house air compressor can supply your needs

Hypothesis B

The big pipe was meant as (storage) tank for the air and the load is ample. In this case you can go for a small precision regulator.

Find out the flowrate and contact a local valve distributor directly.

Is it a 5/8" or 1⁵/₈" tube? I've never heard of the latter as a nominal size, but maybe it's an actual bore?

You can estimate the scfm from the input power and the known pressure rise (1 bar). Better to measure input current to find power, rather than use nameplate data, as the compressor could be rated for a higher pressure rise, the actual rise being determined by the system characteristics. Compressor efficiency likely to be around 50%, lower if it's working well below design pressure. Cross-check with velocity in pipe, expect something like 10 - 20 ft/s based on scfm (ie not actual velocity).

Then specify scfm, inlet pressure and outlet pressure to the regulator supplier.

There'll be information on the web to help select.

Cheers......Codey

To your question 1 5/8 is still produced in copper, steel and PE some versions referring to O.D, others to I.D. - pretty easy to get -

OK thanks........Codey

The compressor feeds the air supply for high volume, low pressure to control paper fed into a printing press. The 1 5/8 tube is the existing feed tube from the compressor through the press. There is no pressure gauge installed. The compressor is rated at 1 bar with the motor rated at 4.5KW at 400 volts (This is a German made machine rated at foreign voltage so it is run off a transformer). The $8,000 compressor is shot and I was trying to find out if house air could be used. We have an Alup air compressor that is currently only running at 31% to maintain 112psi. The closest air line is 1 1/4" piping. So, if a new compressor is $8,000 and piping with a pressure regulator would only cost a couple hundred dollors I thought I would check into it. I know that too small of a regulator would not give the volume. With 1 1/4" piping and regulator would there be enough volume to maintain the 1 bar?

I want to thank you for the answers. Unfortunately a machine that is down losses money and a new compressor had to be ordered and installed before the answer was given. I should have given more detailed information when I started the thread. With the answer given I now have a backup plan if the compressor is down again.

I enjoy reading the discussions. This had been my first question.