Blast pot surging?

[illyco]

Hi everyone!

I purchased some J Blast Supafine and have was blasting with it until the blastpot started, what seemed like, surging. It's almost as if the pressure drops and rises - and I put it down to the media being expendable and has run its course.

I then removed all the J Blast and added some G07 Chilled Iron, and I get almost the same issues. The regulator is set to 70 PSI and the flow is very poor, blasting seems to hardly touch the work; that is until it gets low on G07, then the pressure increases and I feel the power in the nozzle, which shifts the rust as it should.

Was the J Blast going too fine and causing my issues, and now the G07 is too heavy?

I can't seem to get my head around it!

Thoughts or information much appreciated.

 

[rtbcomp]

I take it it's one of the famous ebay 10/20 gallon pots?

It could be a blockage at the nozzle or the mixer. Remove the nozzle from hose and give it a good blast of air. (Close the bottom valve & have side valve fully open)

 

[illyco]

It is indeed.

I checked for blockages. Found nothing.

I have one bag of unused J Blast left. I'm going to use that to see if my symptoms are still there on the first use.

If it is media related. Would Aluminium Oxide be a good media to use? How many times could I possibly reuse that?

 

[rtbcomp]

I've used J-Blast Supafine with no problems. The more it wears down and becomes dusty more likely it is to attract moisture, this will cause blocking. Chilled iron is very susceptible to forming rusty clumps.

I'm currently using crushed glass, again with no problems, I've not tried aluminium oxide.

Also if the bottom valve is open too wide it will allow an excess of media to enter the mixer which will block the nozzle.

 

[jimmyspeed]

I have the ebay pot and it will always surge if you don't turn the sand feed of first

So i always stop the sand then the air (vertical stop cock) and it works fine

Only other way to make it surge is open the sand feed completely and it just bungs up like rtb said

 

[brightspark]

the regulators aka ball valve are none 2 clever ,2 much grit and it pulses in the pipe giving loss of velocity. u realy need 80 percent air 20 percent grit .2 little grit and they tend to stop . the grit should only be used twice and the dust sieved out on the second use and also a bit larger mesh to take all the crappy larger waste particles out

 

[SmartWerks]

These vids should be a sticky?

http://m.youtube.com/results?q=pressure pot 101&sm=1

http://m.youtube.com/results?q=pressure pot 101&sm=1

 

[illyco]

I only have ball valves on the main inlet, and the pipe that feeds the mixer - i removed the bottom valve and connected a 3/8 female-female socket.

Seems fine with the last 25kg of J Blast. Must have been a media issue.

thanks guys!

 

[hedgecutter]

I hired a blasting pot some years ago and had the problems you described when I spoke to the person I hired it from they told me it was moisture in the system and to empty out the grit and just blow air through it to dry it out then refill with grit and away you go which worked so I left it empty overnight ran it empty for about 10 minutes in the morning and it always worked fine.

 

[Premiershipman]

What about inserting a feed tube ?

One of the mods I have seen is inserting a plastic or copper pipe inside the bottom valve and up inside the blast pot.

The tube has lots of holes drilled in it to improve consistent media flow rather than it dropping in in big lumps.

 

[brightspark]

What about inserting a feed tube ?

One of the mods I have seen is inserting a plastic or copper pipe inside the bottom valve and up inside the blast pot.

The tube has lots of holes drilled in it to improve consistent media flow rather than it dropping in in big lumps.

its the cheap ball valve thats the problem. doesnt matter what u do above it. it has to go throught the ball either make or buy a real one or u have to live with it

 

[Premiershipman]

I have a gate valve on mine

 

[illyco]

I have a gate valve on mine

I think I need one of these so I can control the amount of media that comes though into the mixer!

 

[rtbcomp]

I've seen "proper" valves which were a gate valve with a silicone rubber sleeve through it.

 

[brightspark]

I've seen "proper" valves which were a gate valve with a silicone rubber sleeve through it.

ive got one if anyone needs one here