Thought I would ask here about this. Working on Interbulk bag in a box job and have been using a trailer with a donkey engine. Had no problems and averaging 1-1.5hr tip time for 27 tons. Have now been given a new MAN tgx with pto and bower and a trailer to suit. Now every job is taking twice as long. Pressures seem fine, it’s more like a lack of volume of air. Tried running at 800rpm and up to 1100rpm and still no good! Any tanker experts out there? Workshop insist it’s a unit problem and down to W&G who did the work and the office insist it’s the trailer which the workshop won’t have! Arrrgh!
To blow a bag in the box what you need is volume, rather than pressure. In fact you really need a minimum of 1000m3/hr, although 850 will do it eventually. To answer that question you need the make and exact model of compressor. Assuming that the compressor is big enough you should be told the necessary engine speed, the people who fitted the system should have told you. Don’t guess because if you go too far there will be a very big bill. To work this speed out yourself you need to know the exact gearbox you have, the internal splitter ratios, whether it runs in high or low, it’s normally high but there are exceptions notably the Scania GRSO and the gearing in the compressor drive, alternatively a hand held rev counter. I know this isn’t the definitive answer you were looking for but there are a lot of variables. However if it is taking you upto 3 hours at 1100rpm, my guess is that the compressor isn’t big enough for bag in the box; a powder tank will blow quite happily with 700 or even less for fine powders.
The only thing on the trailer which could affect your blowing time is the rotor size and speed. The size is normally pretty standard so you could try playing with the speed control and see if you can make a difference but personally I am with your workshop, it’s far more likely to be the compressor that the trailer.
Well, it’s sorted now. We seem to have parted company with WG and gone back to using Hydraulic Discharge Equipment in Castleford. It was refreshing to go somewhere that listened to what I told them was the problem and then sort it! No " its a driver problem" or " that’s just how it is". Fantastic service from proper engineers. They laughed at the set up that’s been fitted but have made it work.