[WaterFarmFan]

Hello all. I am looking to experiment with short path and want to purchase a used but high quality vacuum pump that can reach 1 micron and below. I have 3cfm & 5cfm single stage pumps that just won't cut it for short path, but make great workhorses for other processes. My budget would be around $1k - $1.5k. Would prefer something that already rebuilt and refurbished. I found this seller that has many brands and options in that price range with a 12 month warranty:

https://stores.ebay.com/provacsalesin...sub=7355357017

I want something that is built to last if I take care of it. Any suggestions? Thanks!

WFF

[mobin]

for durability you can't go wrong with the big ol' welch pumps.

my 1400 and 1405s are awesome workhorses that just won't quit. they take all sorts of crap through the inlet and never seem to care much. i've been known to use them as my "cold trap" and after a power flush, they're easily back into the low miltors again. at .9 and 5 cfm they are adequate for spd work.

however they aren't my go-to for running distillations.

there i'd recommend a direct drive unit. i love my varian sd-300.

pretty much all pumps are going to be of a similar design, so pick something widely used in many industries so re-builds and parts are more plentiful/less expensive.

i've had great luck with industrial/med/lab resellers on c-list and ebay. My most recent pump ended up at a liquidator because someone forgot to see if the dowels inbetween the motor and the pump had holes to go in when they rebuilt it which made it whine, easy fix. $150 pump.

.

https://www.ebay.com/itm/Varian-SD-20.../222633280556?

i was tempted to snag this one myself. 7cfm, adjustable ballast for flushing out nasties from the pump oil or easing up on the suck, compact, and this one is good as new. pc chem labs charges $1200 for that same pump rebuilt.

[WaterFarmFan]

Originally Posted by mobin

for durability you can't go wrong with the big ol' welch pumps.

my 1400 and 1405s are awesome workhorses that just won't quit. they take all sorts of crap through the inlet and never seem to care much. i've been known to use them as my "cold trap" and after a power flush, they're easily back into the low miltors again. at .9 and 5 cfm they are adequate for spd work.

however they aren't my go-to for running distillations.

there i'd recommend a direct drive unit. i love my varian sd-300.

pretty much all pumps are going to be of a similar design, so pick something widely used in many industries so re-builds and parts are more plentiful/less expensive.

i've had great luck with industrial/med/lab resellers on c-list and ebay. My most recent pump ended up at a liquidator because someone forgot to see if the dowels inbetween the motor and the pump had holes to go in when they rebuilt it which made it whine, easy fix. $150 pump.

.

https://www.ebay.com/itm/Varian-SD-2.../222633280556?

i was tempted to snag this one myself. 7cfm, adjustable ballast for flushing out nasties from the pump oil or easing up on the suck, compact, and this one is good as new. pc chem labs charges $1200 for that same pump rebuilt.

Thanks! Welch seems to be built like a tank. Is there any mechanical or other difference besides cfm between the 1400, 1402 & 1405 that makes one more or less desirable? It seems that some have different motors, like GE or Emerson. Is original better?

Thanks for the tip on that Varian. Why would you say it is your go to over the Welchs? Lower micron or easier to operate?.

Also, what you recommend for a used and very accurate vacuum gauge and/or controller? Seems like the Digivac is way overpriced for being a fancy bleed valve - Am I overlooking something???

WFF

[mobin]

Originally Posted by WaterFarmFan

Thanks! Welch seems to be built like a tank. Is there any mechanical or other difference besides cfm between the 1400, 1402 & 1405 that makes one more or less desirable? It seems that some have different motors, like GE or Emerson. Is original better?

Thanks for the tip on that Varian. Why would you say it is your go to over the Welchs? Lower micron or easier to operate?.

Also, what you recommend for a used and very accurate vacuum gauge and/or controller? Seems like the Digivac is way overpriced for being a fancy bleed valve - Am I overlooking something???

WFF

there are size/weight/cfm/oil res differences among welch models. the welch id get for doing everything would be a 1376. 10cfm, big ass oil res. As far as motors, explosion proof would be the only thing i'd actually look for and i dunno if older OE ge motors are better than whatever junk they make now days, but my 1405 ge motor is prob 60 years old.

my varian direct drive is like 5x the cfm of my 1405 at 1/4 the weight, the gas ballast is a lil nob on the side much easier than the big welchs, pulls faster, easier to rebuild, cheaper to run, quieter, doesn't require a designated space. Pretty much all the reasons.

You can do it with a welch, but it's so much nicer direct drive.

At the end of the day, they all do the same thing. If you're gonna get a welch, just be sure to get a big boy: 1397 or 1376 for the cfm.

gagues are another ebay zone. i like to use a pirani/convection at the pump and a thermocouple at the spd.

thermocouple gagues and controllers are abundant so make sure to match the gauge type with the controller (pin out). Varian, MKS, kjl, and leybold/herc are common good companies.

my granville phillips pirani gaugle tube and controllers have been more than adequate for the price point.

my inficon/leybold-herc controller accepts cards for different types of gagues, runs up to 4 sensors at once, and shits signals for data logging or setpoint activations for other equipment like high vacuum valves. you probably don't need all that, but it's nice to have down the line.

[WaterFarmFan]

Originally Posted by mobin

my varian direct drive is like 5x the cfm of my 1405 at 1/4 the weight, the gas ballast is a lil nob on the side much easier than the big welchs, pulls faster, easier to rebuild, cheaper to run, quieter, doesn't require a designated space. Pretty much all the reasons.

You can do it with a welch, but it's so much nicer direct drive.

Good info. I think will get a direct drive unit now while keeping an eye out for a killer deal on an older welch later.

Originally Posted by mobin

gagues are another ebay zone. i like to use a pirani/convection at the pump and a thermocouple at the spd.

thermocouple gagues and controllers are abundant so make sure to match the gauge type with the controller (pin out). Varian, MKS, kjl, and leybold/herc are common good companies.

my granville phillips pirani gauge tube and controllers have been more than adequate for the price point.

So, something like this controller and sensor combo if I wanted to expand in the future? Does it just use a old-school serial port cable to connect?


https://www.ebay.com/itm/LEYBOLD-INFICON-CM3-850-500-G1-VACUUM-GAUGE-CONTROLLER-/362067850976

https://www.ebay.com/itm/granville-phillips-275-mini-convectron-275806-eu-/263186754743

Does the CM3 above allow control over bleed like the unit below:

https://www.ebay.com/itm/Kurt-Lesker...-/222561412067

I appreciate your time! Thanks!

WFF

[mobin]

Originally Posted by WaterFarmFan

Good info. I think will get a direct drive unit now while keeping an eye out for a killer deal on an older welch later.



So, something like this controller and sensor combo if I wanted to expand in the future? Does it just use a old-school serial port cable to connect?


https://www.ebay.com/itm/LEYBOLD-INFICON-CM3-850-500-G1-VACUUM-GAUGE-CONTROLLER-/362067850976

https://www.ebay.com/itm/granville-phillips-275-mini-convectron-275806-eu-/263186754743

Does the CM3 above allow control over bleed like the unit below:

https://www.ebay.com/itm/Kurt-Lesker...-/222561412067

I appreciate your time! Thanks!

WFF

control over bleed? not sure i follow. overpressure? the cm3 will setpoint to stop powering the sensor at certain pressures. that kjl sensor is farrr better. there are combination sensors sporting multiple types of sensors popping up every now and then at affordable prices. some of them even have onboard displays/readouts.

[Goldleaflabs]

Originally Posted by WaterFarmFan

Thanks! Welch seems to be built like a tank. Is there any mechanical or other difference besides cfm between the 1400, 1402 & 1405 that makes one more or less desirable? It seems that some have different motors, like GE or Emerson. Is original better?

Yep they are built like tanks! As long as it goes deep enough any vacuum pump will work. The reason people choose the Welch Duoseal pumps is because they are simple, rugged, and have been almost exactly the same design since the 60's. This makes it so that rebuild parts/kits are cheap and plentiful and many people have experience rebuilding them. You can often take them down to a local rebuild shop. Actually I would be shocked if you found any vacuum rebuild shop that didnt service those belt drive Welch pumps.
The inline pumps are smaller and lighter. Most manufacturers use a very similar design but they are different enough that you might have to send it in for a rebuild.

Originally Posted by WaterFarmFan

Also, what you recommend for a used and very accurate vacuum gauge and/or controller? Seems like the Digivac is way overpriced for being a fancy bleed valve - Am I overlooking something???

WFF

Everything at high vacuum is expensive. The guage is needed but not the controller. Run as deep of vacuum as you possibly can. It will stabilize.

[WaterFarmFan]

Originally Posted by mobin

control over bleed? not sure i follow. overpressure? the cm3 will setpoint to stop powering the sensor at certain pressures. that kjl sensor is farrr better. there are combination sensors sporting multiple types of sensors popping up every now and then at affordable prices. some of them even have onboard displays/readouts.

Sorry. Relatively new to vacuum stuff. When I hear controller, I thought that you would set a point, like 5 or 50 microns, and with the readout from sensor, "bleed off" or regulate the vacuum level to that amount. So that you could have a pump that can pull .25 microns, but if you are doing something other than short path, that might need a more mild vacuum to other tacks. If not, other than connecting multiple gauges and sensor, what does it control?

[WaterFarmFan]

Originally Posted by Goldleaflabs

Yep they are built like tanks! As long as it goes deep enough any vacuum pump will work. The reason people choose the Welch Duoseal pumps is because they are simple, rugged, and have been almost exactly the same design since the 60's. This makes it so that rebuild parts/kits are cheap and plentiful and many people have experience rebuilding them. You can often take them down to a local rebuild shop. Actually I would be shocked if you found any vacuum rebuild shop that didnt service those belt drive Welch pumps.
The inline pumps are smaller and lighter. Most manufacturers use a very similar design but they are different enough that you might have to send it in for a rebuild.

Everything at high vacuum is expensive. The guage is needed but not the controller. Run as deep of vacuum as you possibly can. It will stabilize.

Thanks for the info! Due to shipping costs, would you recommend just buying one local from a repair shop? There are quite a few in my area. I know that there are many models and options, but what is a "steal it" price for a freshly rebuilt and clean Welch?

[WaterFarmFan]

Any thoughts on this? I have had lots of success buying direct from China. Less than $1k including shipping to US. I know rebuilding and parts could be an issue, but this appears to have the specs of a Edwards or Welch direct drive at 4x-5x less price. Could order a seal kit or two when place initial order?

https://www.alibaba.com/product-deta...685176415.html

FX16 technical data

Available pumping speed: 5.0 / 9.0/ 20.0/ 37.0 CFM.
Model: FX16
Free Air Displacement: 4.4 L/s 16 m³/h CFM :9.0
Inlet Diam: I.D. 25mm O.D. 25mm
Cooling mode natural cooling
working voltage(V) Single / 3 phase
voltage and frequencey can be customized

Ultimate Vacuum (Pa) 0.0003Torr/ 0.0004mbar
Noise (dB) 67
Rotating speed(r/min) 1430 r/min
Oil capacity(L) 1.5 L
Dimension(mm) 540X180X300 mm
Net weight (kg) 28.2 kg / 34 kg
Motor power (Kw) 0 .55 kw

I know that is likely a knock off, but I simply can not afford a new E or W, and the cost-benefit ratio is between buying used rebuilt or possibly new from China.

WFF