Reddit reviews Robinair (15115) VacuMaster Single Stage Vacuum Pump - Single-Stage, 1.5 CFM

Refrigeration research engineer here, with a masters in mechanical engineering.

Yes you can dry clothing in a vacuum chamber, but it would take forever.

Between freezing and room temp, the saturation pressure of water is a few kPa (a standard vacuum pump like this would work). It would take forever, the engineering term for several hours or longer, because water has a high enthalpy of evaporation--evaporating water carries away a lot of heat (you've experienced this whenever you sweat)--so the limiting factor will be the temperature of the water and clothing.

To make a long story short, there's a vapor pressure that matches a certain liquid temperature--warmer liquids have a lot of heat so liquid is easily evaporated and the pressure they can sustain will be higher. If you start evacuating gas from the chamber, some water evaporates to make up the reduction in pressure which carries away heat cooling the remaining liquid until the pressure in the chamber matches the vapor pressure corresponding to the temperature of the water.

From the saturation pressure link, the saturation pressure at 0 C is about 0.6 kPa, a cheap vacuum pump will probably be able to pump down to that. Assuming this is the case, your clothing will sit wet at 0 C while water very slowly evaporates. The temperature of the remaining water will be where the heat flowing into the clothing/water from the chamber walls balances the heat the evaporating water carries away. It might be 0 C, it might be -20 C or lower. Regardless this will be a very long time.

The enthalpy of vaporization for water is 2260 kJ/kg. If 100 watts of heat flows into the chamber, it'll take 6.3 hours to evaporate a liter of water. This is the fastest it could possibly take. Fabric is not a good conductor of heat so the parts of fabric that are not touching walls will take a very long time to dry. People who work with vacuum spaces hate getting water in them because it takes so long to get rid of.

Homebrew Materials:

Vacuum Pump Oil

Vacuum Tubing

1/4" Barb x 1/4" NPT Male Hose Fitting

1/4" Male x 1/4" Female NPT Extension Hose

Vacuum Pump

Filters

Spatulas

Magnetic Stir Bar

Digital Hotplate with Magnetic Stirrer

Nitrile Gloves (Better than Latex)

Empty Capsules (Buy Separated unless you hate your life)

Capsule Machine (If you value your sanity, buy more than a 100... I hated my life doing this)

Mohr Pipets

Pipette 10ml

Mortar and Pestle (If you're doing orals, get this... Otherwise, you're playing Russian Roulette with your doses and liver)

Funnel (For pouring into small places)

Alconox (For clean your shit)

Temperature Gun (How hot is my shit?)

Graduated Cylinder (If you measure with beakers, you're a fucking idiot... And you should consider Volumetric Flasks)

Beaker Set

1 Liter Beaker (Because brewing en'masse is better)

Scale (I have a 2kg one, too)

Calibration Weight Set

Calibration Weight 100g (Because you need two for the scale linked)

Vacuum Regulator (Unless you want to filter 9001 times due to broken shit)

Oil (Any USP grade, filtered or unfitlered)

BB

BA

Butyl Stoppers

Flip Top Seals

Crimper

Vials (Unsealed)

Autoclave (Cheaper than an oven, why are you using an oven?!)

Weight Boats (Buy a million of these. They're cheap and useful)

Did I miss something? Probably. Yes.

Without tools, the best you can really do is look for oiliness on the pipe. When you find a joint that feels oily (look for dark colours on the pipe, usually covered in very fine dust. Once you rub the dusty area with your fingers you'll feel the oiliness), spray/pour a small amount of washing up liquid over it and look for bubbles. If there's any refrigerant left in the system, you'll usually see bubbles appear (or over a longer period, foam). Of course if the gas has all escaped already - and we're only talking a couple of hundred grams here - then you won't see any bubbles.

Most domestic gear has no access fitting at all so even locating the leak can be difficult if there's no visual indication. You need to get pressure in there so you can leak test - this means adding a bullet piercing valve (like this).

Then you need to put something in via your bullet piercing valve to raise the system pressure. It's best to use dry nitrogen to leak test to save wasting refrigerant, but since you most likely don't have that on hand you could buy yourself some refrigerant (most likely R134a) and pressurise with that. That's a big no-no here (both disposable cylinders and dumping gas to atmosphere by charging a system with a known leak) but I'm guessing your in the US, and those sorts of laws seem remarkably lax so go for gold. It's not like you'll be ruining MY ozone layer too, right? ;)

You also need to regulate the pressure going in to the system. This is where you need gauges. Connect the yellow line to your bottle, connect the blue line loosely to your bullet piercing valve, purge from cylinder to piercing valve by opening the cylinder tap + gauges tap, and releasing some pressure via the loose fitting, then tighten the fitting and close your gauges tap. Open the bullet piercing valve. Open the gauges tap slowly and give it ~50psi of system pressure.

Then you can go for gold with your soap, or you can lash out and grab yourself some "proper" leak detection fluid (like this), or better yet an electronic leak detector (like this one).

Once you've found your leak, you want to release your nitrogen (or reclaim your refrigerant using a reclaim plant and a spare cylinder), then repair it using an oxy/acetalyne set, or since it's only tiny pipework you can get away with a MAPP gas set.

If it's a copper->copper joint, you're laughing - polish the pipework up with emery cloth, heat the pipe until it's just this side of glowing red, and feed the joint with brown tip silver solder.

If it's a copper->steel joint, then it's a bit more of a pain. You need blue tip silver solder and flux. Clean your joint with the emery cloth, give it a nice coating of flux on every surface you need solder to stick to, then heat it up until it's a fair way short of glowing red. Feed the blue tip solder in and STOP. Unlike brown tip (15% silver) you can't just keep feeding blue tip (45% silver) as it ruins the weld.

Now, since you put on a bullet piercing valve and they leak like a sieve in the long term, we need to replace that with a schrader access valve. Since it's most likely going to be in a straight through piece of pipe, you can save time and grab yourself a pre made access valve in 1/4" pipe. Cut away the hole left by the bullet piercing valve, polish the copper and cut the pipework with a ~10mm gap using a tube cutter. Then slip your access fitting assembly in there, and follow the copper->copper joint procedure.

Of course, now that we've done all that you need to change the liquid line filter drier too. I'd recommend a 1/4" solder in core drier in place of the original copper spun drier because... well, copper spun driers are terrible. Follow the pipe cutting procedure from the piercing valve instructions and the soldering instructions from the copper->copper joint instructions and that's done too. Remember - always try and mount the drier so it's outlet is LOWER than its inlet. This turns the drier into a small liquid receiver and helps ensure a good liquid seal over the capillary tube. Speaking of capillary tubes, if it was inserted straight into the original copper spun drier CUT the capillary, don't try and unsweat it. The chances of blocking it up are about 82.5634% (approximately) when you unsweat capillarys. You're much better off chopping it with a set of capillary tube cutters and ensuring a good clean capillary. The ~30mm of wasted capillary will affect performance, but almost certainly not to any sort of measurable degree.

Then give the system a good evacuation using a vacuum pump and ensure it reaches a good vacuum (sub-500 micron) with a digital vacuum gauge.

Then using a set of electronic scales, charge your freshly evacuated system (remembering to purge!) to the charge recommended by the manufacturer.

Voila! You have just fixed your chest freezer.

..... Alternatively, pay someone to do it for you and/or recycle the components and buy yourself a new one.

Home brew pump and filter question: I'm going to be using the follow pump and filter combo. Do I need a valve to reduce pressure? I'll let the oil cool to Luke warm before filtering.

http://www.medical-and-lab-supplies.com/nalgene-nylon-membrane-complete-unit-150-ml-count-1.html

https://www.amazon.com/gp/product/B005CO9FDW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I've seen a guy use a pressure cooker bottom he got from a thrift store for $3.50. He drilled a hole into the side and epoxied a copper tube to hook to the vacuum. He went to a plastics place and ordered a 3/4" thick acrylic circle that covers the top of the pressure cooker. I think that cost $30. He said he wiped dish soap on one side of the acrylic and let it dry. Then he placed the acrylic on a bead of silicone aquarium goop around the rim of the pressure cooker. The soap allowed him to peel the acrylic plate off the silicone after it hardened.

Anyway, he sprays into a pyrex bowl that fits nicely in the vacuum chamber. Once the obvious butane has boiled off, (he leaves it overnight), he covers the top with the acrylic and purges, using a single-vane vacuum pump. Total cost was about $115.

A couple things come to my mind.

You could look into a vacuum pump like the ones used to draw down AC systems.

Something like this:

https://www.amazon.ca/Robinair-15115-VacuMaster-Single-Stage/dp/B005CO9FDW/

It would probably take a while but I'm sure it would eventually pull water through.

I'm just not sure how they react to water being pulled through the pump, I would hate for the pump to blow when it got the water through.

Is there power down at the lake?

A small utility pump could fill that line up no problem.

You might want to look into a small invertor generator and pump the line full from the far end.

You could also get a small battery powered pump like this:

https://www.homedepot.com/p/RYOBI-18-Volt-ONE-Hybrid-Transfer-Pump-P750/300258095

You would need to cut in a tee near the bottom and add a valve and garden hose female connector but that's very simple with poly pipe.

How much rain do you get? A full 55 gallon rain barrel would probably be able to fill the line up too.

The whole thing is connected to a vacuum pump.. I have some videos that I need to upload somewhere (good anonymous alternative to youtube?). I have no idea what my CFM of my pump is but it pulls through quite literally anything.

And another set of random photos from cooking that night while engineering

New ideas are I need one of these mesh filters. Perhaps 2. They draw pretty hard. These are impossible to do by your self however they may be of use in the 'power assist' mode with the vacuum pump. Definitely need one on the outlet of the first jar to keep depris from the next.


Also think I need to have buffer jars hooked up backwards. The one closest to the vacuum pump empty hooked up to a jar full of water. That way when it sucks through 1 full jar you know that all air in all of the jars has been 'smoked' through. Given enough equipment you could pack 1 massive 1g bowl hook it up to 28 mason jars in series. (You'd have to play around with sizing). And then everyone in the room can carry around a jar full of 'vaporized' 1 gram. Put a straw in it and just inhale in as much or as little time as you want.

Also need to figure out where to get a glass downspout locally to use that instead of the pipe.

> vacuum pump I have is a 1.5 cfm robinair vacumaster

Is this it? http://www.amazon.com/Robinair-15115-VacuMaster-Single-Stage/dp/B005CO9FDW/ref=sr_1_2?ie=UTF8&qid=1404918357&sr=8-2&keywords=vacuum+pump+1.5+cfm+robinair+vacumaste

Did you get the little valve thinggy too? Would that work to regulate pressure? I mean, pretend, for everyone's sake that I am a 5 year old....