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antique diver
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Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Fill Rate and Pressure

Wed Apr 12, 2017 3:58 pm

Obviously you did a good job on your rebuild!

I usually find 2.5 cfm to be an adequate fill rate at home (where I am not it a hurry to get back in the water)... but knowing you, I'll bet you are wanting that 3 cfm mark that Rix has teased you with!

If you wanted to tinker with it a little to get 3 cfm it could be done with an adjustable (variable pitch) pulley on the drive motor. The effective diameter is easily adjusted by moving one side of the drive sheave/pulley in or out on a threaded center core. The closer the two sides are, the higher the belt rides in the groove, making the effective diameter of drive pulley larger. It is easy to fine tune the resulting speed of the compressor.

If you increase the compressor speed, it will also require more power to turn it. The load on the motor increases, so you would need to check the amp draw at high pressure to avoid overloading the motor. See FLA/full load amp rating on motor plate.

Have fun and be careful where you put your fingers.
The older I get the better I was.

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SurfLung
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First Name: Eben
Location: Alexandria, MN
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Re: Fill Rate and Pressure

Mon Apr 02, 2018 2:48 pm

I thought I posted more about this but I must have just sent it to Antique Diver by email or text message or something...

I did get the laser tachometer and sure enough my compressor was not turning fast enough... The manual says it should be 2300 RPM to pump air at a rate of 3 CFM. So I bought an adjustable sheave and replaced the fixed diameter sheave on the motor (sheave is a pulley... I'm getting used to calling a pulley a "sheave"). Anyway, I set it up and turned on the compressor. The laser read something over 2400 RPM. The goal is 2300 RPM. So I adjusted the sheave back one turn and tried again. This time it read 2295 RPM. That's close enough.

I used the compressor all last Summer and just assumed it was pumping at 3 CFM. I recently checked the RPM again and it is still running at 2295. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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antique diver
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Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Fill Rate and Pressure

Mon Apr 02, 2018 9:37 pm

Eben, you are my Star Compressor Student! :D

I still have a lot to learn! Seems like every week I run into some new issue I haven't dealt with before, and I often learn from others a better way to prevent or resolve some service issue. Learning new stuff is good for an old brain.
The older I get the better I was.

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antique diver
Master Diver
Posts: 1876
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Fill Rate and Pressure

Tue Apr 03, 2018 1:17 pm

I should mention that I learned a lot from Eben when he was rebuilding his RIX ! I have never had one apart, but owning one myself I was grateful for the information he gave us as he worked on his. It will help me someday when I have to tear into mine. Thanks, Eben :D
The older I get the better I was.

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SurfLung
Master Diver
Posts: 1462
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Fill Rate and Pressure

Wed Apr 04, 2018 1:14 pm

antique diver wrote:
Mon Apr 02, 2018 9:37 pm
Eben, you are my Star Compressor Student! :D
Exceedingly high praise from the exalted one... :oops:
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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