1 Steam Cars : Phorum
General Steam Car topics
Pressure switch
Posted by: Mark Stacey (IP Logged)
Date: January 28, 2002 06:15AM
<HTML>Someone on the phorum requested information on reasonably priced pressure switchs some time ago? I hope my memory isn't playing tricks.
Span Instruments Plano Texas had a 2 inch non indicating presure switch model PS-124 for about $50 US. I brought one for my steam car 5 years ago but I've done so little running I can't vouch for it's reliability. It appears to be all stainless case and internals.
The design is a bourdon tube with a two turns. When the presure increases the unrestrained leg of the bourdon tube presses on a microswitch. Adjustment is by sliding a plate after slackening a locking screw. Same as adjusting a set of points in a distributer and about as annoying but it can be done.
Cheers
Mark Stacey</HTML>
Span Instruments Plano Texas had a 2 inch non indicating presure switch model PS-124 for about $50 US. I brought one for my steam car 5 years ago but I've done so little running I can't vouch for it's reliability. It appears to be all stainless case and internals.
The design is a bourdon tube with a two turns. When the presure increases the unrestrained leg of the bourdon tube presses on a microswitch. Adjustment is by sliding a plate after slackening a locking screw. Same as adjusting a set of points in a distributer and about as annoying but it can be done.
Cheers
Mark Stacey</HTML>
Re: Pressure switch
Posted by: George Nutz (IP Logged)
Date: January 28, 2002 11:09AM
<HTML>Mark,
Thank you very much---I had asked for sources on this item on the last Lamont update paper. Do you have any idea of the pressure differential between "on-and-off"?
Thanks again, George Nutz</HTML>
Thank you very much---I had asked for sources on this item on the last Lamont update paper. Do you have any idea of the pressure differential between "on-and-off"?
Thanks again, George Nutz</HTML>
Re: Pressure switch
Posted by: chuk williams (IP Logged)
Date: January 29, 2002 05:04AM
<HTML>George--
I have a couple of adjustable high pressure switches that are
manufactured by Barksdale Controls, Los Angeles, which I obtained
from an auction on Ebay. They're adjustable-160-3200 psi, and
have a fixed differential of 35 psi. I'm using one on my steam T,
and it's been working flawlessly for the past few months.
There isn't an address on either the box or the switch, so I
can't give you much more to go on if you were interested in a
similar switch, but if there's any other question I might help with
-let me know.......
Cheers---Chuk Williams</HTML>
I have a couple of adjustable high pressure switches that are
manufactured by Barksdale Controls, Los Angeles, which I obtained
from an auction on Ebay. They're adjustable-160-3200 psi, and
have a fixed differential of 35 psi. I'm using one on my steam T,
and it's been working flawlessly for the past few months.
There isn't an address on either the box or the switch, so I
can't give you much more to go on if you were interested in a
similar switch, but if there's any other question I might help with
-let me know.......
Cheers---Chuk Williams</HTML>
Re: Pressure switch
Posted by: Mark Stacey (IP Logged)
Date: January 29, 2002 05:49PM
<HTML>Hi
I can only quote the manufacturers spec, as unlike Chuk I haven't had enough running time to check out its performance in anger.
Switching differential
to and including 1000psi 5% of range.
1500 psi to 4000 psi 15% of range.
I've been pondering the fairly crude internals of the Span unit and wondering if an ordinary gauges bourdon tube could have a light stiff arm attached to increase the movement ratio, this arm would trip a precsion micro switch. Comments anyone?
Another alternative is to replace a conventional gauge pointer with a disk with sectors cut out a led photosensor unit detects the sector movement. I have plans of this idea somewhere in the files. Memory which is increasingly iffy, tells me it may have been a MSS design?
If you are intersted I'll try to find it.
Cheers
Mark Stacey</HTML>
I can only quote the manufacturers spec, as unlike Chuk I haven't had enough running time to check out its performance in anger.
Switching differential
to and including 1000psi 5% of range.
1500 psi to 4000 psi 15% of range.
I've been pondering the fairly crude internals of the Span unit and wondering if an ordinary gauges bourdon tube could have a light stiff arm attached to increase the movement ratio, this arm would trip a precsion micro switch. Comments anyone?
Another alternative is to replace a conventional gauge pointer with a disk with sectors cut out a led photosensor unit detects the sector movement. I have plans of this idea somewhere in the files. Memory which is increasingly iffy, tells me it may have been a MSS design?
If you are intersted I'll try to find it.
Cheers
Mark Stacey</HTML>
Re: Pressure switch
Posted by: George Nutz (IP Logged)
Date: January 29, 2002 06:49PM
<HTML>Mark,
Thanks so much for the input. I have long suspected that a bourdon tube "spring" would have a lot of give and take to overcome the force it takes to operate a microswitch and the pressure differential it takes to overcome all of this---your 5% differential below 1000psi is not that bad. The present pressurestadt is of a bellows design that gives much more force differential per psi than the bourdon "spring". Have also thought of the cheap "Radio Shack" infrared sensors to remove the hysteresis/put a flag on the bourdon tube in the darkness of the insides---all this takes a lot of time however to futz with. 5% Ain't bad for a $50 unit!! At this time the bellows industrial unit we have(limited to 310psig) is as low as 15psi differential, when running the boiler at near maximum decreases the on-off times that helps the economiser and feedwater control system to maintain stability and good balance.
I thank all for there responses on this matter, Rod and I will move forward one way or the other on the Lamont boiler!
Best, George</HTML>
Thanks so much for the input. I have long suspected that a bourdon tube "spring" would have a lot of give and take to overcome the force it takes to operate a microswitch and the pressure differential it takes to overcome all of this---your 5% differential below 1000psi is not that bad. The present pressurestadt is of a bellows design that gives much more force differential per psi than the bourdon "spring". Have also thought of the cheap "Radio Shack" infrared sensors to remove the hysteresis/put a flag on the bourdon tube in the darkness of the insides---all this takes a lot of time however to futz with. 5% Ain't bad for a $50 unit!! At this time the bellows industrial unit we have(limited to 310psig) is as low as 15psi differential, when running the boiler at near maximum decreases the on-off times that helps the economiser and feedwater control system to maintain stability and good balance.
I thank all for there responses on this matter, Rod and I will move forward one way or the other on the Lamont boiler!
Best, George</HTML>
Re: Pressure switch
Posted by: Mark Stacey (IP Logged)
Date: February 10, 2002 01:14AM
<HTML>Hi
Just wanted to say my idea of alterrng a standard presure gauge to activate micro switchs is NOT my orginal idea. I have just found the reference in the SACA Bulletin March / April 1995. Credit is all due to John Wetz for this idea.
Appologies for not atributing this correctly earlier.
Cheers
Mark stacey</HTML>
Just wanted to say my idea of alterrng a standard presure gauge to activate micro switchs is NOT my orginal idea. I have just found the reference in the SACA Bulletin March / April 1995. Credit is all due to John Wetz for this idea.
Appologies for not atributing this correctly earlier.
Cheers
Mark stacey</HTML>
Re: Pressure switch
Posted by: George K. Nutz (IP Logged)
Date: February 12, 2002 08:00PM
<HTML>Mark,
This switch on a bourdon tube has been around for a very long time, the "New Standard Steam Car" of 1920 appears to have used such a system---nothing is rarely new. By the way just got in a Barksdale catalog and they have a rugged adjustable bourden tube switch with about a 20 psi differential for around $120!!!
Going by dim memory from a few days ago that is.
Your input greatly appreciated, no need to apologize, this is a great discussion board where everyone gives the best they have.
Thanks, George</HTML>
This switch on a bourdon tube has been around for a very long time, the "New Standard Steam Car" of 1920 appears to have used such a system---nothing is rarely new. By the way just got in a Barksdale catalog and they have a rugged adjustable bourden tube switch with about a 20 psi differential for around $120!!!
Going by dim memory from a few days ago that is.
Your input greatly appreciated, no need to apologize, this is a great discussion board where everyone gives the best they have.
Thanks, George</HTML>
Sorry, only registered users may post in this forum.