We have been having some serious problems sucking back a ball on a placingboom rig. It just won't do it.

 Down on the street is a putz BSA 1409 and on the tower is a 24m boom. About 80 meters of 5'' line between the boom and the pump.

Now we've tried several things. When I stop pumping I pump 3 strokes back.. Drain the sections that stand down and put a ball in the endhose. Then suck back. Just to be sure we let the hopper run over last time to make sure we didn't have to stop half way the procedure but still the ball gets stuck on the botom of the tower. From there its still a 40m horizontal line to the pump. I've tried to help with air but didn't help. Pushed with up to 10bar air but no effect.

We also tried one time to not suck back but just only push back a ball from the end and down to the mixer.. No problem ! So now we just decided that will be the method we will use from now on but still... It should be possible to suck back a ball shouldn't it??

Anyone know an answer to this mistery? Only thing I can think of is this: On the botom of the tower the line comes down and then goes up again about 1 foot. then it goes horizontal for about 40m. Its always there where the line goes up these 30cm where the ball gets stuck.

Its a bad construated bit of line there with 2 45degrees bends and a 90 degrees in just 1,5 meters distance. Maybe these bends are badly lined up so the ball gets stuck behind an edge??   

When ball get's to those bends it is dry? maybe you need to use some water or someting.with placingboom  do you not push water from  hopper to endhose?

You have to blow placing boom out with air compressor from boom back down to pump and blow it back in a mixer via diversion valve to stand pipe

having 26 placing boom jobs under my belt i went with last load was pea rock blend mix and never had a promlem

I have never heard of someone sucking a ball back on a placing boom. You need to blow it out with air.

The method I have seen: blow the first sponge back with air compressor, first sponge is either slightly damp or wrapped in a plastic bag and no water is placed in front of it, after the first sponge comes through a second round of sponge/water/sponge (no plastic bag) is blown through, and lastly the diversion valve is switched back to the pump and a single sponge is sucked back to complete the process. Putting water in front of the first sponge can lead to seggregation issues.

Thank you guys so much! I read a story here where someone said you should suck back untill the hopper is full than switch the deversionvalve and pump in the mixer... Than switch the valve again and suck... and so on and so on untill the ball had come back. But I guess that story was a wrong one.. 

Gaby I know a lot of guys say you should do the ''waterwash'' thing but we've tried that and we got the worst disaster on our hands. We washed the hopper.. put a bal in the line and started pumping clean water. We ended up with a line full of rock and sand.

So now I know air is the way to go. Blow back from the endhose to the mixer. It would have been much safer to be able to suck back with the pump but Ill mannage to do it with air safely to as long as we use the right equipment.

Realy nice to hear some opinions from some experts   

Fix the line where the elbos are,even if you add another 20ft of system.So nothing is uphill.

What kind of elbows do you have at the bottom of the stand pipe, I have had nothing but issues with plugging pipeline with short radius 90* elbows, Can you change to med to long radius 90's ?

This would help with pump pressure and blowout problems. There are a lot of other potential issues, the slump, the Mud can all play a role in the ability to cleanout, I have had Hiteck chem mixes that are total problem children pumping and blowing out.

If you HAVE to suck back I would recomend blowing a good ball with a bit of water 3 to 5 gallons after the line is empty to ensure a good clean. Either up or down what ever fits the site needs.

keep in mind the higher you go the more trouble you will have with tight restricted bends at the bottom of the stand pipe.

You guys are right. Its a very bad solution with all the elbows. Reason is that when they where buiilding the system they where missing 1 long radius 90. They where also missing a guy that could weld so they could make the pipes the right length. So they had to use a load of 90 and 45 elbows to make it all fit... Realy a shame.

We are concidering to do the job right and change it..

sucking back causes cavitation and segregation. leave system full. add ball and controlled air through a diversion valve back into truck if possible. if not reverse stroke slow , use air pressure as head pressure. Whenever poss. wet mud before blow back. do the math. "you can pretty much just count strokes when you prime to know" so you dont put wet mud on deck. Basically use controlled air.

Pretty sure I have posted this link before, but hear it is again.

http://www.youtube.com/watch?v=Hz5Z0YULdrk

+ some pics because I cannot type 1000 words;-)

Next time consider to buy another pump e.g. Spanish SEBHSA(search in Google,pls) with water tank of 600 litres, High-pressure, high-output air compressor, driven by direct hydraulic motor, for cleaning delivery pipeline and 150 litres compressed air tank!

These stationary pumps have also: Fully hydraulic automatic control system without stroke terminals, electrovalves or other electrical switch devices. Foolproof operation in any climate.

Here in Poland i know a few clients who operate with these type of pumps

Operators also can do it with only air:

http://www.ioperator.eu/viewtopic.php?t=189