[SEL] Binks Air Compressor Data Needed

[Curt]

Francis,
The loading and unloading scheme you describe is a very common practice 
in industrial electric reciprocating compressors. I have 3 compressors 
feeding a single tank set up at the house. Two are on air switches and 
the switch turns the compressor motor on and off to maintain tank 
pressure between a min and max setting. The third compressor is 
controlled with a pneumatic switch that also has a min and max setting. 
However, this switch simply unseats the intake valves on the LP cylinder 
as JB mentioned. This method has to be employed on compressors that are 
loaded a high % of the compressor capacity. If you are using 70 or 80% 
of the compressor's capacity, you would be turning the compressor back 
on within seconds of switching it off. This would wreck the windings on 
an electric motor shortly. Hence why pneumatic unloading was developed, 
to save motor windings.

If you are going to use the compressor for light loading, you can 
convert it over to motor switching. You will _have_ to utilize the built 
in pneumatic unloader you already have to avoid damaging the motor when 
starting when there is pressure in the tank. You can do this using a NO 
air switch (3 way) that keeps air on the unloader when there is no 
voltage present. Then when the motor is turned on, the relay will be 
energized turning the air off to the unloader. You will also need a 
needle valve on the vent for the 3 way valve to allow you to slowly 
bleed air off the unloader circuit. This will allow plenty of time for 
the compressor motor to come up to speed, before the intake valves are 
allowed to reseat.

As mentioned I have both setups feeding a common tank. When painting or 
something that is irregular use of air, I'll use the motor on/off 
compressors. When sandblasting, I'll use the pneumatic load/unload 
compressor. If a lot of air is needed all three can be run at the same 
time, giving about 60 CFM at 100psi. This allows use of the outside pot 
blaster with a 3/16" nozzle. That removes the crud rather quickly!
About 1/2 way down on this link is a picture of all 3 compressors.
<http://www.oldengine.org/members/holland/images/Rotophase/rotophase.htm>
Curt Holland
Gastonia, NC

jbcast at charter.net wrote:

>>Hi List,
>>I have an older Binks Lo Boy compressor.  Instead of an  electrical pressure 
>>switch to control the predetermined output,  it has some sort of an internal 
>>clutch to disengage the compressor from  pumping more air when the set pressure 
>>is reached.  When it is in the  latter mode, when maximum pressure is 
>>reached, the motor/compressor pulley  continues to run without a load.  
>>Does anyone have any technical data or parts lists for this type of  
>>compressor?  Is there any other make that uses a similar control  system?   
>>
>>    
>>
>Francis, I've only seen tis on gasoline powered compressors, they use an unloader to lift the intake valves. This allows the engine to keep running while the compressor freewheels. Your unit may have been designed for a gasoline motor, I don't se any advantage on an electric set. The larger screw compressors run continuously, unloading when necessary, but these circulate oil with the air and seperate it.
>J.B. Castagnos 
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