older picture

[bnelson]

Heres a try at posting a picture. This is an older picture posted from my work. Will post an updated one from home tonight

[jsmith]

that looks good.

Can't see how you change the orifice or reverse the flow.

Perhaps you could explain the workings of your bench.

[bnelson]

Jim,

No orifices to change, since this bench uses and LFE (laminar flow element). It creates a differential that is nearly linear based on flow, versus other devices that create exponential delta p. It is rated at 429cfm. LFE is the gold object in the pipe below the power panel in the middle. The large round section houses the filter for the LFE (to avoid fouling the foil honeycomb inside). The end of the large round section is removable to gain access to the filter for servicing. There are 8 ametek vacuum fans on top of the plenum, with room for 3 more. Each has a check valve housing to prevent back flow if it is not running. Vertical manometer on left measures test depression, incline manometer measures dp across LFE. Scales are in 1 inches. Round gauge is an absolute pressure gauge (barometer) for flow calc corrections for the LFE. All manometers are Meriam Instruments as well as the LFE. The round gauge is Wallace-Tiernan inches and half tenths of hg. Will write more later.

[Mouse]

That's an awsome setup!

What size pipe leads into and out of your LFE?

John

[98-1074649673]

I'm sure others would like to hear how the motor check valves work if u care to share? I know I sure would like to hear how they work?

Did you say the LFE was purchased or did you make it?

Nice looking bench!!

[bnelson]

The pipe leading from the test hole down to the filter plenum is 5" o.d. mandrel bent exhaust tubing.....16ga I think if memory serves. The outlet from the LFE into the fan plenum is 4" o.d. mandrel bent exhaust tubing. BTW this tubing is available real reasonable at a large truck parts and repair shop. The ones I have are by Fleet Guard Products......Fleetguard.com I think. All of the tubing flanges are made from 1/4" plate with 8 equally spaced 3/8" bolt holes. I'll take some more pictures of the details later and post.........the batteries in my camera just died. The check valves are some of the same 5"o.d. tubing that has been welded to a 1/4" plate flange on the bottom. Inside, down about 1/2" from the top is a piece of 1/4" x 1" flatbar welded across the i.d. of the tubing with the 1" width facing up. It has 3 holes drilled in it. One in the center to oil the top motor bearing in the fan and the outside two to screw the check valve to the 2 tapped holes in the top of the fan motor frame. On the side of the check valve tube I welded on a bracket for the flap hinge. The bracket is made from a piece of 3 1/2" x 1/8" wall square tubing. I cut it in half first to make a channel, where the legs are about an inch long. The bracket is about an 1 1/4" tall and the top sits about 1/8" below the top of the tubing. The flap is made from a piece of 2a sided 1/2" plywood, cut out with a circle cutter in the drillpress. On the bottom of it I glued a piece of 1/16" neoprene rubber. The flap hinge is just a regular old door hinge thats been re-drilled to move the screw holes to better fit the bracket on the side of the tube and the flap diameter. Speaking of diameter, the flap is 5 1/2" o.d. The wood screws into the top of the flap were cut off on the bottom with a hacksaw before installing the rubber. The screws on the bracket side are just regular machine screws and nuts in slightly oversized holes. To true the top of the tubing where the flap sits, I had to chuck each valve up in the lathe and face the top after the bottom flange was welded on.

BTW, all of the Meriam instruments I bought on ebay for a fraction of what they sell new for. I could never have afforded any of it without buying them this way. A word of caution: never buy an LFE unless you can get ahold of the calibration papers that go with it, otherwise it is useless because the papers contain all of the correction factors and formulas that you need to calculate the flow. All LFE's are flowed at the factory and given a correction factor that you plug into a formula. Each and everyone of them are all a little bit different. They compare them with a master and then assign two unique factors to the LFE for doing calculations based on how it compared to the master.

I have pictures of the filter plenum under construction and will post along with others if anyone is interested.

Here is a current picture. (well, if it uploads anyway!!)

[bnelson]

Here's a picture of the check valve parts. This is one of the unfinished ones for one of the 3 future fans......if ever I need them.

[bnelson]

Here is a close up of the check valves. Note that you have to undo the brush holders and reassemble once the check valve tubes are in place. The ends of the brush holders only clear by about an 1/8" of an inch. The flange as well as the cord entrance are sealed with clear bathroom silicone.

[bnelson]

Heres another picture. The tubing out of the LFE is 4" mandrel bent truck exhaust. The rubber hose is marine exhaust hose. Plate flange that attaches to the bottom of the plenum is homemade from 1/4" plate and welded to tubing. There are t-nuts / flanged nutserts inside the plenum floor that the 3/8" flange bolts thread into. Flange gasket is made from 1/8" neoprene sheet rubber. The 2 nuts and threads sticking out of the plenum floor are 9/16" all-thread that extend throught the plenum roof. They have washers and nuts on both sides of the roof and floor........to stiffen both against collapse.

[bnelson]

Here is a picture of the top of the test hole plate. Typical plate flange on bottom as used on other connections. Flange holes are blind tapped holes in bottom for 3/8" bolts. Test hole plate itself is 8" square and started out 3/4" thick.....closer to 5/8" now after machining in the lathe to true it up.....was a piece of scrap and not real pretty at first.....but didn't feel like buying a new piece! Bolt holes to hold dummy cylinder on top are 5/16" on 5" square pattern. I.D. of test hole is 4-7/8". Counter sunk holes to hold plate to bench are 5/16" with t-nuts again on bottom of bench top.

[bnelson]

Here's the bottom. (I hate my camera cause it makes my welding look way ugly!! must be like they say a camera adds 10 pounds to a supermodels picture!!)