PTS Flowbench Forum

OK by popular demand Machinist-parrot joke.

A machinist works alone all day and wants some one to talk to but he can't stand people so he decides to get a parrot. He goes to the local Pet Store and they have two parrots. They look identical! One is $1500 and one is $300. He asks the pet store owner what the difference is since they look exactly alike. The pet store owner states that the $1500 parrot id flawless but the $300 parrot has a .015" flaw (hump) in it's beak. The machinist says "That is nothing, I have mics so I can just machine that .015" off and no one will know." The pet store owner tells him that may not work as sometimes there is a .002" hump in the membrane inside and if he takes the whole .015" off he will go into the membrane and kill the parrot. The machinist says, "I will just give it the .002" clearance and no one will see that, so just give me the $300 parrot"

Next day he comes storming into the pet store again and says "Give me the damn $1500 parrot!" Pet store owner says machined too far and killed it didn't you. Machinist says "No I crushed it's head in the vise!"

Good joke John, liked it. As far as the mmo compensation I would ay that if you were to use the Roco86 spread sheet you can input th sg . of your fliud and set the incline to 90 degrees and the well dia. should be your tube I.D. and you should get a comprehenvise scale. " I think."

Hi Guys,

So I wanted to dig up a thread about water alternatives as opposed to creating a new one. That way most of the other water alternatives are already in the thread. This was the newest thread on the topic so here goes...

I was searching for alternative to water with as close to a specific gravity to water as possible. I have MMO so that was the "obvious" choice but at .876 I was hoping I could get closer. DOT5 silicone seemed the next logical choice at .958. So I began looking for DOT5 at local part stores and I found Gunk Motor Medic DOT5 (Part # M-4011). I looked up the MSDS and found it has a S/G of .990!

The chemical make up is MUCH different than the other DOT5 fluids I researched (all with the .958 S/G). The MSDS comparison shows the same viscosity of the fluid so it should flow as well as any other DOT5 does.

I have yet to try it out as I have been SUPER busy at work and on a project for a Church event this weekend. I *hope* to have a chance to test it this weekend some time. I'll keep you guys posted.

One day this all won't matter to me as I will own a PTS digital manometer but for now every time I get the money saved up I have to buy new tooling or replace older stuff.

I hope digging up an older thread was the best option.

Chris

Great find, I think the old standard of fluid gauges is hard to beat for the club racer or weekend DIY especially when you have spreadsheets that can be pre programmed to do the flow math and SG correction.

Rick

1960FL wrote:Great find, I think the old standard of fluid gauges is hard to beat for the club racer or weekend DIY especially when you have spreadsheets that can be pre programmed to do the flow math and SG correction.

Rick

I'll second what Rick stated . . .

Thanks guys.

Testing now. I had to remount all my manometers so I am double and triple checking everything. I'll post up results later.

Chris

Ok so here is the report.

The fluid seems to work really well. After verifying that everything was installed correctly and the gauges were zeroed I began testing. The results are this fluid seems to yield results right in line with what I was getting with water. well, technically I had Dwyer green gauge concentrate that you mix with distilled water (which means it evaporates pretty quickly).

According to my previous notes when re-testing my two test orifices I get the same CFM reading with the new fluid as I did with water. That's good news.

So one possible issue is the fluid is much more viscous than water. The gauges take a bit of time to completely re-zero. This doesn't seem to effect the reading though as I let the bench run for several minutes and the reading was within about a 1/16th on the incline. I did have to back the motors down some (very little) after about 60 seconds but after that readings were steady.

All in all I would say this could be a good alternative to water. The jury is still out on any evaporation issues but I am hopeful this won't be an issue.

I hope this is helpful.

Chris

Ok, so I have a rather disappointing update...

After more time with is fluid I would say it is most likely not a good solution (neither would normal DOT5 at that point). The fluid is just to viscous. I *thought* I had zeroed out the vertical manometer but as it turns out I was about an 1" off. Here's what is happening...

The fluid is viscous enough that it clings to the tubing and takes a LONG time to fully drain back and normalize. I filled the manometer and let it setting for at least a 1/2hr as I noticed it would creep for a few minutes. Anyway, I went back to the barn again Saturday to do some more work and the stupid thing was at a little over 1"! I drained out some fluid and let it settle. Turns out it take OVERNIGHT to get the fluid completely normalized! (in a 48" U-Tube manometer) So yesterday I did a test (after the fluid had normalized overnight), I pulled 28" on a test head and let it run for 5 or 6 minutes. I then shut the bench down and watched the fluid. It was 1" off at first. After about 5 minutes it was still about 1/4" off.

So basically I believe that when I am pulling 28" on a tests piece I am not really getting 28" as the fluid has not completely drained down the one leg of the U-Tube. I believe that means I am technically pulling harder on the test piece (until the fluid would catch up). The issue is the longer I test the closer the reading with be. This is certainly throwing off my lift curve at least some. The worst part is there is no way to know how much the manometer is off at what time...

In conclusion, I think any fluid with this much viscosity should be deemed not a good alternative.

Thanks,
Chris

Thanks for the report back!

well that sucks was hoping we would be looking at a new fluid other than MMO or water.

Rick