My Rix SA-6 Diesel

[iain/hsm]

@iain/hsm I don't know what's a "good" gauge .

Well thats an interesting question, I guess the answer is knowing the difference between the $5 hydraulic gauge from China selling at $15 on Amazon or the $20 hydraulic Gauge made by WIKA Germany selling at $30
agains an $80 gauge with Rix written on the dial.

The important things to note is in general purpose 2-1/2" cheap hydraulic gauges is as follows
1. They all use brass threaded stems fixed in with screws and yet call it a stainless gauge
2. They mostly if not all use two rivets to attach the dial
3. They state no information as to the accuacy of the gauge
4. The bourdon tube is a single copper curve lead soldered to the movement
5. No calibration is possible
6. The case material is stainless iron 304 stainless

By contrast the gauge quality used on the Rix engineering specification for the SA-6 is as follows:
1. They are built fully of 316 stainless designed for gas service (not hydraulic)
2. The stem is also 316 stainless steel and fully TIG welded to the case
3. The stem has a small "frit" or flow restrictor fitted to the inlet to reduce adabatic compressive forces on the movement.
4. The movement is "Dampened" with a pulsation dampener
5. The indicating needle is knife edge pointer
6. The dial is screw mounted
7. The bourdon tube is stainless small bore coiled design
8. The gauge movement is adjustable for calibration and certified class printed on the dial
9. The coil is TIG welded to the movement
10 The case material is stainless Steel 316


And for a little more you go into the Mil-Spec range of dial indicators with as follows;
1. Safety Pattern Certified
2. Safey Glass
3. Front flange blow off back safery design
4. Shock Resistant
5. Solid Baffle wall between you and your face from the internal movement
6. Vibration Dampened in addition to pulsation
7 Mirror reflex dial

We should do a post on proper gauges suitabe for compressors

 

[iain/hsm]

Now before you start the thing you have a number of considerations and checks to do before yanking on the starting coil
Again its something we should have done years ago and I do have a detailed manual outlining all these components but it was done for the military so I'm really limited in letting it out as a PDF wild on the internet. I will really need to do another version and remove all the reference and details of the missile components that are attatched or get in even deeper trouble with our timid left.

Oh and dont order any parts for it yet. IMHO you can verify operation very simply without cost by going through a verification check list 20 minutes before starting. Basic cleaning, visual inspection and one measurement of a blue spring another 10 mimutes
Then hand turn only and verify 4 bearing clearance and a single spring compression,

Then start the machine against a blocked outlet (scuba tank turned off) and verify blow by, valve performace leak rates to separators interstage pressure etc.

To be honest the only real interesting gauge I would consider is an interstage pressure gauge on the 2nd stage separator you can see all you need from that.

 

[rob.mwpropane]

Now before you start the thing you have a number of considerations and checks to do before yanking on the starting coil
Again its something we should have done years ago and I do have a detailed manual outlining all these components but it was done for the military so I'm really limited in letting it out as a PDF wild on the internet. I will really need to do another version and remove all the reference and details of the missile components that are attatched or get in even deeper trouble with our timid left.

Oh and dont order any parts for it yet. IMHO you can verify operation very simply without cost by going through a verification check list 20 minutes before starting. Basic cleaning, visual inspection and one measurement of a blue spring another 10 mimutes
Then hand turn only and verify 4 bearing clearance and a single spring compression,

Then start the machine against a blocked outlet (scuba tank turned off) and verify blow by, valve performace leak rates to separators interstage pressure etc.

To be honest the only real interesting gauge I would consider is an interstage pressure gauge on the 2nd stage separator you can see all you need from that.

If you can send me a copy of the pertinent information that would be awesome. I do not need to know, nor do I care about missiles (unless you can turn them into scuba tanks, then I'll take a liking).

I do not have any fittings after the OPV on the unit. No whips, gauges, or anything. I do have the extra tower to go after, but have not ordered any fittings to go with it either.

So I basically have a Rix up to the OPV, then a fiter tower sitting there. No hoses, nada....

 

[rob.mwpropane]

Well thats an interesting question, I guess the answer is knowing the difference between the $5 hydraulic gauge from China selling at $15 on Amazon or the $20 hydraulic Gauge made by WIKA Germany selling at $30
agains an $80 gauge with Rix written on the dial.

The important things to note is in general purpose 2-1/2" cheap hydraulic gauges is as follows
1. They all use brass threaded stems fixed in with screws and yet call it a stainless gauge
2. They mostly if not all use two rivets to attach the dial
3. They state no information as to the accuacy of the gauge
4. The bourdon tube is a single copper curve lead soldered to the movement
5. No calibration is possible
6. The case material is stainless iron 304 stainless

By contrast the gauge quality used on the Rix engineering specification for the SA-6 is as follows:
1. They are built fully of 316 stainless designed for gas service (not hydraulic)
2. The stem is also 316 stainless steel and fully TIG welded to the case
3. The stem has a small "frit" or flow restrictor fitted to the inlet to reduce adabatic compressive forces on the movement.
4. The movement is "Dampened" with a pulsation dampener
5. The indicating needle is knife edge pointer
6. The dial is screw mounted
7. The bourdon tube is stainless small bore coiled design
8. The gauge movement is adjustable for calibration and certified class printed on the dial
9. The coil is TIG welded to the movement
10 The case material is stainless Steel 316


And for a little more you go into the Mil-Spec range of dial indicators with as follows;
1. Safety Pattern Certified
2. Safey Glass
3. Front flange blow off back safery design
4. Shock Resistant
5. Solid Baffle wall between you and your face from the internal movement
6. Vibration Dampened in addition to pulsation
7 Mirror reflex dial

We should do a post on proper gauges suitabe for compressors

So would the WIKA made gauges from Germany be a happy median?

 

[rjack321]

So would the WIKA made gauges from Germany be a happy median?

I get my gauges from McMaster Carr, they are a bit more but at least have specified accuracy. I dont get NIST certified gauges obviously, scuba compressors aren't NASA equipment lol

 

[iain/hsm]

So would the WIKA made gauges from Germany be a happy median?

WIKA is certainly one of the better volume producer manufacturers in Europe and they also make a budet range brass/stainless for around £15 GBP/ €17 to compete with the far east. But they also own the best IMHO USA gauge manufacturs on the planet that of Rolyn now called 3D intruments now called WIKA USA

But before you go with us lot over here in Europe do also consider some of your own home grown gauge manufacturers in America.

3D Instruments - WIKA USA

Also consider these guys they also manufacture some of the best pressure gauges available and were used in the calibration and testing of your SA-6 compressor

High Performance Pressure Gauges | Perma-Cal® Industries

For a more budet range have a look here.

https://www.stewartsusa.com

Further down the barrel then these folk

Home Page

For the cheapskate farm hand look here

https://www.weissinstruments.com/assets/liquidfilledbulletin.pdf

Another good quality well made USA gauge manufacturer is Ashcroft

Ashcroft Pressure Gauges - Overview

And to cap the list off used by every diver when servicing a regulator you have Dwyer

Home | Dwyer Instruments

All those listed above made in your own back yard so to speak what's not to like.
Before you go down the Amazon made in China junk.

 

[iain/hsm]

scuba compressors aren't NASA equipment lol

No but the SA-6 is NASA equipment.

Together with a number of other much larger gas compressors
He is in good company it's just not all rocket science I guess.

 

[RayfromTX]

One like is not enough. Love your post sir.

 

[rjack321]

No but the SA-6 is NASA equipment.

Together with a number of other much larger gas compressors
He is in good company it's just not all rocket science I guess.

Yea I know they are used in more sophisticated stuff I was just teasing that a 50psi error for scuba fills isnt a big deal

At least as a primary gauge, I would agree that getting something from a reputable supplier with a specified accuracy is wise. I would have to go check who actually built the "mid quality" gauges I got from McMaster which still seem to be going strong after 13+ years of use.

 

[rob.mwpropane]

I know there's some back and forth, but I can't tell you guys how appreciative I am of the knowledge you have shared.