Hi all. Can somebody give me the difference between a tanker and a vacuum tanker please. I’ve got an interview and they want experienced vac tanker drivers but I’ve only done normal tankers (I’ve told them this so it can’t be that important). I just want to go into the interview with a bit of know lance on them so I don’t look a complete waster.
Thanks in advance.
A vac tanker is usually (but not always) loaded by creating a vacuum inside it which will draw the product into it. A normal gp tanker (forgetting spirit cars or gas tankers) use internal pressure to discharge a load (again forget pump discharge for a moment) and any sort of vacuum to these tanks is a no no as they are designed for pressure from within, whereas a vac tanker is designed for pressure from the outside, which is why you’ll see they have supporting ribs around the outside of them.
normal tankers normally have a lobe pump for loading or tipping and a compressor to pressurise the barrel to tip. lobe pumps aren’t very good at sucking air though, so you have to get the product to the pump, then it will ■■■■ fine. Dry running will also destroy the lobes, as they need the product to lubricate them.
a vacuum pump ■■■■■ the air out of the barrel so the difference in pressure inside to outside forces the product into the barrel. most vacuum pumps drip oil into the pump as it’s working so the vanes seal, the drippers that drip the oil, want setting around 1 drip every 2 / 3 seconds. this oil is used up and not returned, so the level needs regular checking and topping up. a ball valve closes the path to the pump once it’s full so that only air goes through the pump. change the handle to the other side will blow into the tank to discharge and when the handle is in the mid position it will vent the barrel. if the pump isn’t sucking right, especially after being stood for awhile, chances are the vanes are stuck, quite a straight forward job to sort out, but depending on who you’re working for they might not want you touching things like that!
As Stevie said if its stood a while the blades in the exhauster pump might have stuck, 8blades in all slid in at 45 degrees to a steel rotor inside the casing, , shouldn’t have to worry about that tho thats what maintenance is for, but if its a gully emptier always check on the nearside before you try and vac the tank there is a valve usually 2" between the front and rear compartments,.
This is the interconnecting valve, it links the vac side to the clean water side always make sure the handle is in the 6 o clock position otherwise it will never vac as the vac side isnt sealed.also NEVER think you pressed vacuum and press Pressure, when I worked at Whale making vac tanks they sealed a vac tank left it on pressure and it blew the manhole lid 80 yards across the field.
Jeff