OCCRA
Go to Post If it's the loss of American lives that concerns the nation, why not campaign aggressively against smoking, or improve automobile safety? At least then, the benefits will be tangible, and substantially more significant to the well being of the locals. - Tristan Lall [more]
Home
Go Back   Chief Delphi > Technical > Pneumatics
CD-Media  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 08-14-2018, 03:11 PM
Zem's Avatar
Zem Zem is offline
Registered User
AKA: Braeden (I speak for myself, not for my team)
FRC #3461 (Operation P.E.A.C.C.E.)
Team Role: College Student
 
Join Date: May 2018
Rookie Year: 2010
Location: CT & RIT
Posts: 33
Zem will become famous soon enough
Pressure not rising smoothly

Hello CD

My air system is not building pressure smoothly. The needle on the stored pressure gauge shakes back and forth about 15 to 20psi as it goes up. This worries me because my pressure switch now does not read 120psi until the true pressure in the tanks it about 135 to 140psi.
Can anyone please help me? Is there something wrong with my compressor?
By the way I am using this compressor from amazon: https://www.amazon.com/Viair-90-Comp...dp/B002A65JR6/
Reply With Quote
  #2   Spotlight this post!  
Unread 08-14-2018, 04:16 PM
GeeTwo GeeTwo is offline
Somebody Else
AKA: Gus Michel II
no team
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
Posts: 5,962
GeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond reputeGeeTwo has a reputation beyond repute
Re: Pressure not rising smoothly

Are the compressor and tank connected by a long thin tube, and is the gauge at the compressor end? If so, this is probably just the regular cycle of the compressor; like all displacement pumps, it generates surges of pressure. (E.g. a heart beat). To get a more even measurement, locate the gauge (and pressure switch, BTW) as close to the tank as possible. If you don't have an accumulator tank at all, you should.
__________________

If you can't find time to do it right, how are you going to find time to do it over?
If you don't pass it on, it never happened.
Robots are great, but inspiration is the reason we're here.
Friends don't let friends use master links.
[Quoting brennonbrimhall]: We design a new robot every year, but we can't forget that we also design a new team every year as folks come and go.

Last edited by GeeTwo : 08-14-2018 at 04:18 PM.
Reply With Quote
  #3   Spotlight this post!  
Unread 08-14-2018, 04:57 PM
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1996
Location: Wheeling, IL
Posts: 11,113
Al Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond reputeAl Skierkiewicz has a reputation beyond repute
Re: Pressure not rising smoothly

Braeden,
This is normal behavior while the compressor is running. However, it is unusual for the system to shut off using the pressure switch above 120 PSI. It is possible for there to be a restriction between the stored pressure gauge and the pressure switch that would delay the turn off of the compressor. If you use teflon tape (I hope you do) then it is possible for the tape to have blocked the entrance to the pressure switch. Most teams will place the pressure switch and the stored pressure gauge very near each other. Failure for the pressure switch normally occurs when the diaphragm in the switch has a leak. This leak can be heard near the switch when there is pressure in the system and the robot has been disabled. When in doubt try another switch.
__________________
Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
________________________
Knowledge is power. Power UP!
Reply With Quote
  #4   Spotlight this post!  
Unread 08-14-2018, 04:58 PM
Tom Line's Avatar
Tom Line Tom Line is offline
Don't lay blame. Fix probems.
FRC #1718 (The Fighting Pi)
Team Role: Mentor
 
Join Date: Jan 2007
Rookie Year: 1999
Location: Armada, Michigan
Posts: 3,197
Tom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond reputeTom Line has a reputation beyond repute
Re: Pressure not rising smoothly

These pumps are piston pumps. The gage needle shaking is normal.
Reply With Quote
  #5   Spotlight this post!  
Unread 08-14-2018, 11:16 PM
EricH's Avatar
EricH EricH is offline
New year, new team
FRC #1197 (Torbots)
Team Role: Engineer
 
Join Date: Jan 2005
Rookie Year: 2003
Location: SoCal
Posts: 22,044
EricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond reputeEricH has a reputation beyond repute
Re: Pressure not rising smoothly

My personal preference on locating the gauge is at the far end of the high-pressure side of the system from the compressor: just before the regulator to low pressure. Then a second gauge on the regulator (for the low-pressure side). Takes all the shaking out, and also puts the gauges closer together so it's easy to check both at inspection. Some vibration is normal, but it should slow down as the system pressurizes.
__________________
Past teams:
2003-2007: FRC0330 BeachBots; 2008: FRC1135 Shmoebotics; 2012: FRC4046 Schroedinger's Dragons

"Rockets are tricky..."--Elon Musk



Reply With Quote
  #6   Spotlight this post!  
Unread 08-15-2018, 06:53 PM
Zem's Avatar
Zem Zem is offline
Registered User
AKA: Braeden (I speak for myself, not for my team)
FRC #3461 (Operation P.E.A.C.C.E.)
Team Role: College Student
 
Join Date: May 2018
Rookie Year: 2010
Location: CT & RIT
Posts: 33
Zem will become famous soon enough
Re: Pressure not rising smoothly

This has helped thank you. I moved my gauge and pressure switch behind the tanks and it works great now.
Thank you.
Reply With Quote
  #7   Spotlight this post!  
Unread 08-15-2018, 10:13 PM
Jon Stratis's Avatar
Jon Stratis Jon Stratis is offline
Mentor, LRI, MN RPC
FRC #2177 (The Robettes)
Team Role: Mentor
 
Join Date: Feb 2007
Rookie Year: 2006
Location: Minnesota
Posts: 5,124
Jon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond reputeJon Stratis has a reputation beyond repute
Re: Pressure not rising smoothly

Quote:
Originally Posted by Zem View Post
Hello CD

My air system is not building pressure smoothly. The needle on the stored pressure gauge shakes back and forth about 15 to 20psi as it goes up. This worries me because my pressure switch now does not read 120psi until the true pressure in the tanks it about 135 to 140psi.
Can anyone please help me? Is there something wrong with my compressor?
By the way I am using this compressor from amazon: https://www.amazon.com/Viair-90-Comp...dp/B002A65JR6/
For others that may come across this thread in the future... I've seen bad gauges cause confusion in the past. I had a team whose compressor "never" shut off - aka the high pressure gauge read 140+ and we stopped it. We confirmed correct working of code by manually triggering it by shorting and opening the wires, we replaced the pressure switch, and finally when we replaced the gauge we got different readings that showed everything was working correctly. So, if you see a discrepancy between the pressure switch and the pressure gauge, remember that either one could actually be the problem!
__________________
LRI: North Star 2012-2016; Lake Superior 2013-2014; MN State Tournament 2013-2014, 2016-2018; Iowa 2017; Northern Lights 2018; Great Northern 2018-2019
Division LRI: Galileo 2016; Tesla 2017; Archimedes 2018
2015: North Star Regional Volunteer of the Year
2016: Lake Superior WFFA
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 05:38 AM.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi