Mako unit with 1991 Bauer Compressor Identification help

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Jayson Kempf

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Location
Alaska
# of dives
50 - 99
I have a 1991 Mako breathing air unit with a 4 stage 1991 Bauer Compressor unit on it that I am wanting to convert from 3 phase to single to run at home. It has Baldor 3 phase 7.5 HP motor that I want to attempt to run with a heavy duty 4-8 hp Phase-O-Matic convertor. My RPM will be reduced as they say I'll only get 2/3rds HP at same rpm from motor and decrease pulley by 1/3rd. Will the decrease in RPM's be ok to run the compressor? Bauer serial number is 91/4396/07
 
I would run that off a VFD, way way way more efficient
 
I have a 1991 Mako breathing air unit with a 4 stage 1991 Bauer Compressor unit on it that I am wanting to convert from 3 phase to single to run at home. It has Baldor 3 phase 7.5 HP motor that I want to attempt to run with a heavy duty 4-8 hp Phase-O-Matic convertor. My RPM will be reduced as they say I'll only get 2/3rds HP at same rpm from motor and decrease pulley by 1/3rd. Will the decrease in RPM's be ok to run the compressor? Bauer serial number is 91/4396/07

A static phase converter, I presume you mean? (Phase-O-Matic makes rotary converters too.) Those cost a significant chunk of the cost of a single-phase motor that will run the compressor, particularly if you find one used.

A VFD is certainly a better solution than a static phase converter, as is a rotary phase converter, but the VFD is a lot cheaper than a rotary phase converter that size or a replacement single-phase motor. Had my compressor come with a 3-phase motor rather than a gasoline engine, it would have a VFD on it instead of a single-phase motor.
 
phase converter is only $500 compared to rotary at well over a $1000. I can get single phase motors between $700 and $1000. didn't price out VFD yet but will look into it. I think I have the KAP-14-7,5 H. the phase converter will run at 2/3 HP so with motor pulley reduced by 1/3rd it will spin compressor at slower RPM more like the KAP-5,5 H. I hope, ideas?
 
If you are going to derate it to 5 hp, then just put a 5hp single phase motor on it. Rotary phase converters burn allot of power and a 100 amp service may have too much resistance to get it started, massive inrush.
 
OK I'll explore VFD's. I can get one to run it for around $800-900 range. I had it at a electrical shop and was going to have them put a single phase motor in it for $912 but they said the Solid state convertor would work with less than 50amp service. They said that other options are more efficient for power consumption but as little as I'll use it ( like 10-20 bottles a year) the convertor option would be cheapest way to get it going. I was really hoping to find what I need to do on the compressor to spin it at lower RPM's and if that's ok. I have the convertor ordered already after talking to a few electricians familiar with motors and running equipment with them. I hope it works enough to get it up and running. later this year I'll see about boosting performance if I need.
 
Why not just replace the motor with a 7.5 hp single phase one?
 
I got the compressor for free, it was retired from the fire station, still in working order but 3 phase. I only dive here once a month around so I only needed 20-30 bottle fills for my 16 year old and myself, I can get free bottle fills mostly, so I am trying to keep cost down. My 16 year old really wanted this as a project so he has been looking at ways to get it rolling and this was an item that came up as possible solution for the least expensive one. I listed all my options and costs for VFD, Rotary Convertor and single phase. It is a MAKO air module with a three bottle bank that we would fill off of mostly. The compressor would run slower and I wasn't sure about what I would need to do for the compressor, It looks like there is a 5,5 model that would be similar to what mine will be after I loose 1/3 of the power out of the 7.5 hp motor. Was wanting to get any info on compressor I think its the Bauer KAP-14-7,5 H 1991 model. I can find the year the serial number and I know the motor HP and pressure it is set up for so that's what I think it is.
 
Your are over complicating it. It doesn't matter if it fills a bit slower, in fact desirable.
 
OK great, is there anything I'll need to change on the compressor? It has oil pump for oil supply to 4th stage. It looks like maybe I'll need to adjust it? I've been digging for info on it and it doesn't have much as for a minimum RPM. I was wondering what kind of oil do people use? MAKO or Bauer and if I have to order it, or is there alternatives?
 
https://www.shearwater.com/products/perdix-ai/

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