Actual 120 PSI for Storage

[JesseK]

The software for pneumatics is pretty sweet - plug everything in, initialize something and away it goes.

The problem is, the cutoff of the automated switch happens anywhere between 110 and 115 PSI. How are teams able to get 120 PSI of storage volume? Is that switch adjustable?

(caveat - I haven't done more than a cursory look over pneumatic rules since 2011, which is when the electronics team took over that duty).

[wilsonmw04]

Originally Posted by JesseK

The software for pneumatics is pretty sweet - plug everything in, initialize something and away it goes.

The problem is, the cutoff of the automated switch happens anywhere between 110 and 115 PSI. How are teams able to get 120 PSI of storage volume? Is that switch adjustable?

(caveat - I haven't done more than a cursory look over pneumatic rules since 2011, which is when the electronics team took over that duty).

we noticed the same thing. a year or two ago there was a thread that stated that the switches were calibrated in the factory and could not be adjusted by us (even though there is an adjustment screw on the switch). I'll try and search for the thread and repost it here.
found it:
http://www.chiefdelphi.com/forums/sh...nason+swi tch

[Kevin Sevcik]

Originally Posted by wilsonmw04

we noticed the same thing. a year or two ago there was a thread that stated that the switches were calibrated in the factory and could not be adjusted by us (even though there is an adjustment screw on the switch). I'll try and search for the thread and repost it here.
found it:
http://www.chiefdelphi.com/forums/sh...nason+swi tch

Rules on this seem slightly grayer this year. There's not specific prohibition on adjusting the switch, just that it needs to operate to prevent over pressuring the system. There's the general rule prohibiting modification of pneumatic components and there's no exception for adjusting the pressure switch, but there's also no exception for calibrating the pressure relief valve, which is suggested by a blue box later on.

Maybe Q&A adjustment of the pressure switch just to be sure?

[Tom Line]

The switch can be manually adjusted, however it requires breaking the factory seal around the outside of the switch itself - which has rendered it illegal in the eyes of inspectors in the past. Your mileage may vary.

[Oblarg]

Originally Posted by JesseK

The software for pneumatics is pretty sweet - plug everything in, initialize something and away it goes.

The problem is, the cutoff of the automated switch happens anywhere between 110 and 115 PSI. How are teams able to get 120 PSI of storage volume? Is that switch adjustable?

(caveat - I haven't done more than a cursory look over pneumatic rules since 2011, which is when the electronics team took over that duty).

Try different switches until you find one that is set a bit higher.

As far as I know, there's no way to adjust them.

[wilsonmw04]

Originally Posted by Oblarg

Try different switches until you find one that is set a bit higher.

As far as I know, there's no way to adjust them.

We tried that and out of 4 that we have we never got one to 120. only 115.

[Oblarg]

Originally Posted by wilsonmw04

We tried that and out of 4 that we have we never got one to 120. only 115.

I can't recall if I've ever actually gotten one set to 120. Some are certainly a lot better than others, though.

[Al Skierkiewicz]

Everyone,
The pressure switch may not be adjusted per R76.
The adjustment is to set the position of the microswitch internal to the assembly for operation. It is set at the factory to overcome the differences in microswitch operation from unit to unit. Through testing, the switch is actually a lot more accurate than it appears, as the gauges used on most robots do not have the precision needed to read 120 psi with any repeatability.

[FrankJ]

Originally Posted by wilsonmw04

We tried that and out of 4 that we have we never got one to 120. only 115.

The little screw on the side is a locking screw. You adjust the switch by turning the barrel. Once you run out of range, the switch stops working. (which means adjusting to the high side the compressor will stay on.) The part number of the legal switch calls for a set pressure of 115 PSIg rising. So most switches will turn off close to 115 psi. They turn back on based on the hysteresis of the switch which isn't as precise. As Al said, they are nonadjustable by rule.

[Sperkowsky]

We also have the same issue. Ours usually says 112 PSI.

[zinthorne]

Ours only reaches 105 psi.

[FrankJ]

Originally Posted by Sperkowsky

We also have the same issue. Ours usually says 112 PSI.

Most of the ones I have seen turn off between 115 & 112 indicated. I suspect that Nason adjusts them to turn off before 115. Your pressure gauge is almost certainly a class B which are accurate to 2% of span in the middle. So assuming a 160 psi gauge that 112 +/- 3.2 psi.