@RayfromTX mine are actually having their fans removed. Too ineffective at that slow speed IMO. I am likely going to put a variable speed electric fan on the shroud to keep air flow maximized during slow operation. I do have thermal cutoff switches ready to put on each of the heads and set to 400f. Teflon starts degrading at 500f, so want to keep it significantly cooler than that.
Thankfully with big banks and CCR, I can let it run at 1cfm and just let it go.
At least removing the cooling fan will make it run quieter I guess LOL
Now from memory the SA-6 has used at least six (6) different cooling fan designs over the years that I can remember
And only four main types are available as stock fan designs that I can photograph as examples.
The current SA-6 for sports diving uses a moulded generic white six (6) bladed fan
The Mil-spec SA-6 uses a hand built black eight (8) bladed zero degree pitch
The SA-6 scientific Pure Air SA-6 uses as above but with a 30 degree pitch angle
For low RPM using a paddle shaped blade would be a consideration designed for generating fanned pressure
while the wing tip trailing edge reduces noise and generates a lower threshold of wake turbulance
In a nutshel for Mil-spec use its peddle to the metal and compete with an F-15 in rattling the roof while for recrational use its as quite as it needs to be to pass noise limits and not interfere with your Iphone ringtones.
I should look up the stall speed graphs for the mil-spec units as we built them if l get time
1. The fan inside the specially designed SA-6 shroud work together to incease air pressure from the fan blade tips over to the back of the shrould housing while the increased air pressure blowing around the cooling coils allow for a pretty decent amount of heat exchange between the two.
On cooling coil one off the 1st stage hot side this is to reduce the "Approach Temperature" into stage 2 inlet side.
But critically not so much to the point at which it would induce water vapour to condence out over the 2nd stage head. Then out of the 2nd stage hot side the cooling coil 2nd stage is when most of the water is "knocked out" of the gas stream and condenses out into the collection separator tower due to the sudden loss in temperature along the cooling coil and again another advantage of going oil free over oil lubricated is manifest as water cooler faster and more efficiantly than an oil film.
On the final stage this is to reduce the approach temperature into the filter (if fitted) and bring the temperatures down to within hand hold limits allow.
Now the big question here is:
1. With your required temperature limit (400F)
2 Where and how are you measuring this temperature.
Reason I ask is for consideration that what you are measuring may not be what you need to know
For example measuring the head temperature is not the same as measuring the gas temperature no way close.
And the position or point of measurement is critical for a accurate reading but more important to achieve a relivant reading.
Bauer for example to asses filer life measure the skin temperture of the cool filter shell externally with the B-Timer
Making you totally unaware of the real temperature that makes the real marked effect as to filter life expectancy. Measure the gas temperature not the filter shell.
Others measure the skin temperature of the compressor stage head again with no idea of the real gas temperature.
Others know the temp of a bolt screwed into the metal head. Why?
All are not accurate readings of the real need to measure actual gas temperature inside the gas stream at the point it comes off the cylinder head discharge valve side with a suitable pressure proof RTD
That is the point you dont want to see 350F IMHO
Frankly I think you were ill advised regarding this temperature business.
1. Measure the gas temperature not the head temps
2. OK to set at 350F to start off with but it is critical IMHO to monitor the compressor in real time and see what number you are getting. Then reduce the 350F setting down to say a few degrees above the maximum you are normally seeing. That way and I assume you have incorporated a high temperature cut out switch when the compresor cuts out high temp you can asses the reasons Hot day, extra high pressure, Dog sleeping in front of the fan shrold etc and make the judgement call to wake the dog.
Also get a good quality digital room temperature and humidity reading monitor as well I will try and look up some suitable models. Iain