We thought we would take a little time to go over some items related to pumping concrete, shotcrete or even grout that we get a lot of questions on: cleaning out.  Presumably, if you have a pump, have used it at least once and it’s still in working condition, you have at least the basics of cleaning out.  Now this is not a “How To”, but we wanted to talk about a couple of the tools that can make this a more successful and/or more productive experience. To properly clean out your placing line or hose, you need to insert a barrier and then push it through with either air or water.  Things that have been used for a barrier include wadded-up newspaper, rags or scrap foam.  Do you ever wonder where all the lost sofa cushions go on the side of the freeway?  While these work to a certain extent, the foam clean out balls do a better job and are uniform so they cover all sides of the hose or pipe. 

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Concrete will always be harder than foam, so if you don’t get full coverage you will have concrete that will be left behind and harden in your line.  With luck, this will come out as a chunk of concrete on your next pour, but it could also get stuck in place and additional concrete will build up over time. Different hardness of balls can be used depending on your job specifics.  If you have a long push, have been pumping all day or have fast-setting mix, you will need a harder ball than if you are just cleaning out a 25’ grout hose.  For the best cleaning, we suggest Go-Devils.  These are plastic bullet-shaped projectiles that have several fins around the circumference that scrape clean the sides of pipeline and hose.  While these work very well, they are likely to become dangerous if you are not using a Go-Devil Catcher when they exit the end of the line.  These catchers are also a good idea for the foam balls to keep them contained.  Both Go-Devils and foam balls can be reused. 

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As far as the starting end of the hose, the blow out fitting is a cylinder that has a coupler on one end to mount onto your line with a standard clamp and an opening with a valve, usually ¾” or ½”, to control the flow of air or water into the line.  This is fairly straightforward but we do want to mention that if using air, you should have a blow off valve to allow you to release the air pressure in the line should your clean out ball or Go-Devil become stuck.  It is best if the end of this valve venting to the atmosphere has a section of pipe with the threaded end cut off to direct the air blast away from the operator.  This will also prevent anyone from inadvertently connecting anything (hose etc.) to this coupling that would prevent the full release of air pressure from the line.  While many people fabricate their own, we stock blow out fittings configured for use with either air or water.