Diablo pump "Do not run dry"

[marshbrewer]

I got one of the above for Christmas, which I understand is a branded version of a fairly common pump type . How careful do I need to be about the above instruction; does it mean do not run dry at all, ever, not even for a couple of seconds? If so, how do you prime it? Or does it mean do not run dry for a period of time, so it's fine to allow it to pump air whilst priming? I don't want to damage it on first use.

 

[Its 6pm somewhere]

I just keep the pump at a lower level than the kettle (kettle on a dolly so I can move it around and pump down on the ground), open the valve and the liquid will naturally run into it. By the time I've reached for the switch for the pump after opening the tap it's primed

 

[Agentgonzo]

If the pump runs dry, it'll spin much faster than intended. Apparently some pumps can tear themselves apart (probably not homebrew pumps) in this scenario. The wiring (increased load) and pump components (increased friction) can overheat, but this is unlikely to happen in a few seconds.

I have always assumed that a few seconds of running dry by mistake is unlikely to do much damage at all (could be wrong). I've had a few times when my grainfather pump has run dry for a few seconds before I turned it off or got wort going into it, and it's not suffered in any way.

 

[Its 6pm somewhere]

Highly recommend putting on quick disconnects or camlock adapters if that's your preference, makes life a lot easier and well worth the few quid. I have one long and two short pieces of 1/2 inch tubing with quick disconnects. One short one from the kettle to pump and can run the long hose from the pump for recirculating the mash and then switch to a short one out of the pump to the cf chiller and long hose direct to the fv from the 'out' of the chiller.
I've run mine dry for a few seconds at the end of the transfer and haven't had any issues yet

 

[marshbrewer]

So, I'm going to show my ignorance here, but how does the pump prime without being switched on. Doesn't the pump stop the air in the tube passing so you get an air lock?

 

[Agentgonzo]

Doesn't the pump stop the air in the tube passing so you get an air lock?

In a lot of cases, no. It doesn't fully stop the flow

 

[marshbrewer]

OK, understood. Thanks everyone.

 

[hoppyscotty]

In a lot of cases, no. It doesn't fully stop the flow

Or pumps will often have a bleed at the highest point of the pump head...either a spring loaded bleed or a screw type.

When they say don't run the pump dry they usually mean for extended periods...not an issue if the pump suddenly runs dry for a few seconds as you empty a vessel before switching off the pump...just dont go and leave the pump unattended so it runs for an extended period of time if the vessel empties, or the supply line becomes blocked or something.

 

[MashBag]

So, I'm going to show my ignorance here, but how does the pump prime without being switched on.

Keep it lower so it fills.

Suck on it

or fill with a funnel.

Doesn't the pump stop the air in the tube passing so you get an air lock?

Not all pumps are the same.
Impeller pumps don't create a vaccuum they move a liquid.

With careful use there is no need to ever run it dry.

 

[MashBag]

https://www.angelhomebrew.co.uk/diablo-pumps-240v/386-ahb-diablo-plus-homebrew-pump.html

Defo reads like an impeller pump. I like them, because they have two speeds.. Flow through (slower) and pumped (obvs faster)

 

[Buffers brewery]

I have very similar pumps. I wouldn’t recommend running them “bone dry” as the internals (of mine) are plastic, housing and rotor. When I’m transferring wort from mash tun to kettle, the pump runs “dry” for a few seconds when the mush tun is empty. The pump can handle that.
As these type of pumps are not self priming they should be mounted below the source liquid level so that the pump fills with water by gravity. One thing to remember is the exit side of the pump needs to be vented in order for the pump to fill up. They don’t handle air-locks in piping either so make sure pipes and hoses are routed to avoid these.