Preparing High Voltage Oil. / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Preparing High Voltage Oil.

1 2 3 next

Move Thread

LAN_403

Patrick

Sun Jul 08 2018, 08:07AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Drawing a high vacuum is ideal do de-gas a insulating oil. But can boiling oil accomplish a useful result at least similar? not as good of course.

the_anomaly

Sun Jul 08 2018, 01:12PM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

Not sure about de-gasing, heating is recommended for brake fluid to remove moisture, I am guessing most oils will release moisture when heated.

Ultrasound can be used to help de-gas, it is used at least for heavy potting compounds. I don't believe anything other than a high vacuum will be very effective.

Patrick

Sun Jul 08 2018, 04:06PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

i guess vacuum pumps are getting cheap and i need it for carbon and fiberglass'ing building any way.

I was looking at this one :

with free shipping from Los Angeles.

the_anomaly

Sun Jul 08 2018, 04:58PM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

Looks good to me! I found a name brand pump Robinair on craigslist for cheap. I would ask the seller what the fitting size is. 7/16-20 is the standard HVAC fitting. There is a larger fitting size for 1/2 inch hose which is commonly used but I forget its dimensions. I mention the fitting size because if you buy HVAC hoses to connect it, the hoses are mostly standardized. I bought an off brand manifold guage set and the fittings did not match any hoses I had...

Sulaiman

Sun Jul 08 2018, 07:38PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

My pump looks like it came from the same factory as yours (China)
- no complaints so far but I hardly use it. It seems fairly rugged.
Mine is the dual-stage version, 0.3 pa, but I can't measure such low pressure.
I have no idea whether or not the internal pumped lubrication helps or not.
The extra low pressure has been of no use to me yet,
but if you are considering vacuum electronics it may be worth the difference.
(that is how I justified the extra cost to myself :)

Be sure to buy extra oil, some for an emergency flush,
some to flush the newly manufactured (in China) precision instrument of any debris.

For short runs you can use small diameter (>=4mm i.d.) tubing,
long runs with large vessels need larger diameters for lower pressures - or a long time
(like trying to change the voltage across a large capacitance via a large resistance)
I changed the HVAC connector on mine for a 1/2" hose connector - I may go larger.

Most of the de-gassing YT videos that I've watched use a single-stage pump
and it should be easily able to evaporate water down to ice.
So I can't recommend 'upgrading' to a dual-stage,
that pup looks good to me.
(no idea if that is the cheapest in your area but the price looks good to me)

Based on other vacuum pumps that I have - most of the noise comes from the exhaust port, (along with a little oil vapour)
So if you can pipe-away the exhaust it will be much quieter.
As I rarely use this type of pump I have not moddifed the exhaust port of mine yet.

Patrick

Sun Jul 08 2018, 09:36PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

this is my plan :

i was thinking this way its all nice and neat and storable. hose collapse is also something i worry about.

I guess there should be a valve in between the dial and pump ?

Im also looking for collapse resistant hose. all i see on ebay or amazon is the silicone engine vacuum hose, i dont think those are collapse resistant. would normal shop air hose work ? or will that "inhale" external air ?

the_anomaly

Mon Jul 09 2018, 01:50PM

Registered Member #19 Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168

You will need a valve and you have it in the correct spot.

The pump should have a switch on it so you can at least skip that.

I like the idea of a hose rack for storing the hose. Since the pump has a handle, you can bolt it to the skid and just carry the whole unit by the pump maybe.

Patrick

Wed Jul 11 2018, 02:32AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

so what do many use for the connections ? im thinking a hose barb with screw hose clamp with the shop hose that is normally pressurized for air-tools ?

Sulaiman

Wed Jul 11 2018, 04:24AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Although some plastics (e.g. ptfe) can be porous to gasses,
at the pressure that you will be using it will not be significant.

Tubing that I can use in winter may collapse during the summer.

I am using some very thick walled silicone tubing that I happened to have
but the most popular type is clear braided pvc. e.g.

A little grease on the hose barb gives a good vacuum seal,
hose clamps are not really required as vacuum makes the hose grip the barb.

A vacuum-safe container with some oily stainless steel wool in front of the pump is a really useful item;

. the volume acts as a 'reservoir' of vacuum
. the oily wool catches dust
. the volume can 'catch' any liquid or foam accidentally sucked by the pump

For de-gassing I strongly recommend having the trap,
if needed only once it pays for itself,
and it is not difficult for me to have an accident

Patrick

Fri Jul 13 2018, 12:20AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

ok Sulaiman i will be following those bits of advise. Ill add a trap-tank too.

Now how long do i hold an ultra low vacuum on permanent transformer oil, and two part epoxy ? 2 minutes ? 2 hours, 2 days ?

ill degas the A and B parts seperate, then mix with out bubbles (sort-of) then degas mixed for like 20 minuets (75-90 pot life) then start to pour or toss in the dry transformer, and let the vacuum in.

does this sound good ?

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob