Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 65 users online :: 4 registered, 0 hidden and 61 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Peak pressure measurement.

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Unread postAuthor: pizlo » Sun Mar 09, 2008 4:47 pm

It just gives you the peak applied.
  • 0

User avatar
pizlo
Brigadier General
Brigadier General
 
Posts: 783
Joined: Fri Dec 22, 2006 7:27 pm
Reputation: 0

Unread postAuthor: squarles2007 » Tue Mar 11, 2008 6:54 pm

now i know this wouldnt be very accurate but it could be helpful in knowing when your mix is about to be to much for your chamber.

lets say you know that your chamber has an estimated bursting pressure of 1000 psi. you get a pressure relief valve and set it for oh say 800 psi, and on the outlet of the pressure relief valve you "cap" the pipe with a piece of aluminum foil or similar material and fire your gun if the alumminum foil is still there you didnt go over 800 psi and you "prolly didnt send steel shrapnel into your neighbors car at 500 mph
  • 0


squarles2007
Private
Private
 
Posts: 6
Joined: Tue Feb 26, 2008 11:32 pm
Reputation: 0

Unread postAuthor: willarddaniels » Wed Mar 12, 2008 1:09 am

jimmy101 wrote:Do you have a part number or specs (or web link)? Is it a peak pressure recorder or does it gives a continous output?


DigiBar PE 200 by HBM. This units give continuous pressure, tare function, stores min and max pressure in memory until cleared. Also graphs increasing and decreasing trends- If I ever should need to use that function...
It can be used in constant temps of up to 158 F.
Reads up to 1000 bar at a typical .1% calibration margin.
Battery operated, I also have the DC adapter.

I found some sites that reference it, but since I have the manual I haven't looked too hard.
  • 0

If you're 20 and not a liberal, you don't have a heart. If you're 30 and not a Conservative, you don't have a brain.
User avatar
willarddaniels
1st Lieutenant
1st Lieutenant
 
Posts: 286
Joined: Wed Jan 31, 2007 2:34 pm
Location: Idaho
Reputation: 0

Unread postAuthor: D_Hall » Wed Mar 12, 2008 9:29 am

squarles2007 wrote:lets say you know that your chamber has an estimated bursting pressure of 1000 psi. you get a pressure relief valve and set it for oh say 800 psi, and on the outlet of the pressure relief valve you "cap" the pipe with a piece of aluminum foil or similar material and fire your gun if the alumminum foil is still there you didnt go over 800 psi and you "prolly didnt send steel shrapnel into your neighbors car at 500 mph

First off, if your pipe has a burst pressure of 1000 psi, you're a dmaned fool to take a dynamic system to 800 psi.

Secondly, you'd have to be VERY careful about what sort of relief valve you used as inertial forces in the valve may very well keep it from opening even if it DOES see 800 psi (but only for an instant).

All that said, a common trick in laboratory guns is to use masking tape on the breech. Basically you put tape on all potential gas paths. You shoot the gun... Yeah, if the tape's still there all your o-rings and such held.
  • 0

User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: squarles2007 » Wed Mar 12, 2008 9:31 am

I was just throwing out some numbers for illustrative purposes
  • 0


squarles2007
Private
Private
 
Posts: 6
Joined: Tue Feb 26, 2008 11:32 pm
Reputation: 0

Unread postAuthor: D_Hall » Wed Mar 12, 2008 9:47 am

squarles2007 wrote:I was just throwing out some numbers for illustrative purposes

Fair enough. In which case the concept is sound but you'd be much better off going with a burst diaphram or similar rather than the relief valve. Oh, and yeah, tape works better than foil for the simple reason of handling/wind/etc.
  • 0

User avatar
D_Hall
Donating Member
Donating Member
 
Posts: 1759
Joined: Thu Feb 07, 2008 7:37 pm
Location: SoCal
Reputation: 6

Unread postAuthor: psycix » Wed Mar 12, 2008 9:57 am

D_Hall wrote:
And why does the response time matter?

If it takes 0.05 s for your gauge's needle to spin from 0 to 100 psi when hit with a 100 psi event, that needle will only register events that last at least 0.05 s. If the event lasts for (say) 0.005 s, you're never going to know that you got hit with 100 psi.


Okay, lets say were were about to record an event that lasts a short time. We expect to reach about 100 psi.
The time the event lasts is too short for our gauge to actuate.
So whatta we do?

Our setup is like this:
[CHAMBER]-[CHECK VALVE]-[GAUGE]
We pre-charge the space between the checkvalve and the gauge up to 90 psi.
When the event occurs the needle only has to spin from 90 to 100 :)
Just an idea.
  • 0

Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

Spudfiles steam group, join!
User avatar
psycix
Donating Member
Donating Member
 
Posts: 3684
Joined: Mon Jun 25, 2007 7:12 am
Location: The Netherlands
Reputation: 0

Sponsored

Sponsor
 


Unread postAuthor: jimmy101 » Wed Mar 12, 2008 1:59 pm

willarddaniels wrote:DigiBar PE 200 by HBM. This units give continuous pressure, tare function, stores min and max pressure in memory until cleared. Also graphs increasing and decreasing trends- If I ever should need to use that function...
It can be used in constant temps of up to 158 F.
Reads up to 1000 bar at a typical .1% calibration margin.
Battery operated, I also have the DC adapter.

I found some sites that reference it, but since I have the manual I haven't looked too hard.

Looking at the data sheet (http://www.disensors.com/HTML/pdf/PE300.pdf) there really doesn't seem to be a sample rate spec. The closest I see is "Maximum measurement frequency at current output Hz approx. 1.3". That is way too slow, the gauge needs to respond within perhpas 1mSec for it to be of any real use for measuring the chamber pressure in a spudgun as it fires. That is the intended use isn't it?

Is there more information in the manual?
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3127
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Previous

Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], Google Adsense [Bot], Yahoo [Bot]

Reputation System ©'