hole saw lubrication for cutting aluminum tank

[duncan]

I will be mounting the unit around the top of the tank level - tanks about 3-400mm deep.

Not sure I follow the last part of you 'pressure picture' - if I go in to (come off) the spare inlet then I am on the other side of the filter so not subject to change if the suction pressure the other side of the filter is increased due to clogged filter surely?

 

[cliff]

What is important is the height the metering pump has to raise the fuel from the fuel tank to the pump so if your tank is in the bilges below the sabin sole and the heater is mounted below deck level you could have 6' or more to lift the fuel - IIRC the metering pump willl not do that and you need a remote tank higher up in the boat.

Yes, If you use the spare inlet you are in effect connecting to the line upstream of the primary filter and so will nor be affected as much by the engine drawing fuel as you could be if connected to the spare outlet. The majority of yachts have the fuel tank level with the engine or in many cases above the level of the engine hence there is a positive pressure head on the inlet side of the primary filter

It might be easier to understand if you look at it along the lines of:
for fuel to flow through a filter you need a pressure differential between the inlet and outlet. With a new filter this will be small for a given flow rate. As the filter element becomes clogged this differential must increase to maintain the same flow rate. In the case of the primary filter this is achieved either by a pump at the tank providing a few psi positive pressure to the feed line or by gravity feed and the suction provided by the lift pump. By tapping into the inlet side you are utilising any positive pressure there but if you tap into the outlet side youcould have a problem if the lift pump suction exceeds that which the metering pump can overcome. This suction will increase as fuel demand (flow rate) rises or the filter becomes partially clogged.

PM sent
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"Artificial intelligence is no match for natural stupidity"

 

[Sans Bateau]

This must be the most talked about hole in marine history! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

 

[duncan]

sorry.............. /forums/images/graemlins/crazy.gif

any tips on cutting the hole for the exhaust in the hull?.......only joking!!!!!!!!

 

[Sans Bateau]

Good luck for tomorrow!

 

[Wayward_Son]

To be honest with you about the cutting of the hole (remember the hole?), with my experience as a machinist and the relatively small hole through relatively thin material, I would recomend a coarser tooth than you will find on a bi-metal holesaw and wouldn't worry about lubricant. The finer pitch will clog up with aluminium and start the process of plastic deformation. A decent wood holesaw has enough waste material capacity to blow right through the tank and the tailings are large enough to easily see and clean up. However it is just one hole so you definitely could push the bi-metal blade through, but it may not be useable again.

 

[cliff]

[ QUOTE ]
This must be the most talked about hole in marine history! /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

[/ QUOTE ]Naw - I thought that was the hole in the Titanic!
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"Artificial intelligence is no match for natural stupidity"

 

[DavidGrieves]

The fitting I got from a local diesel fitter. He got me a shorp piece of nylon tube, an olive, and the nut to screw it into the filter. I took the blanking blug with me, the fitter knew instantly what size nut and olive I needed. I joined the eberspacher fuel pipe to the new nylon tube with the short piece of rubber pipe supplied in the kit.

Looking at your profile and seeing the size of engine involved I might have one reservation! Could the eberspacher metering pump overcome the negative pressure created by the fuel suction pump? It might stop eberspacher working when main engine was working hard.

I bet you wish you hadn't started this thread!

 

[billcowan]

Yeh these are the punches to use, pilot hole can be made using a square section tapered punch (a piece of 10mm square steel bar sharpened to a point) just bashed in with a hammer - crude but very effective NO SWARF at ALL!

 

[billcowan]

NO - The most talked about hole was the one in the side of the Titanic.

2nd place went to Lady Hamilton. (Nelson's bit, not Christine) /forums/images/graemlins/smirk.gif

 

[cliff]

I was trying to be diplomatic by not specifying which hole I was refering to. /forums/images/graemlins/smirk.gif /forums/images/graemlins/grin.gif
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"Artificial intelligence is no match for natural stupidity"