dear JMDufour,

Is there anymore information from the nameplate?

Roots type?

Maximum pressure drop?

pre inlet?

blower volume?

leakage volume?

The 150 kW is related to the volume AND the pressure drop.

I the pressure drop is known, then a quite accurate estimate of the air delivery can be made.

If you have the pressure drop let me know.

take care

teus ■

I belive Holmes is now part of the ROOTS producr line.

I checked all my ROOTS data and couldn't find a reference to that specific model, but a 1030 at that speed will deliver approximately 4625 ICFM, assuming your at sea level and using STD conditions.

Hope this helps ■

dear MJDufour, hello Jack,

Based on the required power (150 kW) and the assumed blower displacement (4625 ICFM # 130.96 m3/min), I made a blower calculation.

From that calculation follows that the maximum pressure is approx 0.5 bar (500 mbar)

see attachment

have a nice day

teus

PS

when are you changing to ISO standard units.

(kg, meter, second)

Attachments

holmesblower (ZIP)

■

As I originally mentioned, I couldn't find the specific model you referenced so I use a 10x30 Roots machine as a reference.

If your machine is actually a 10x33, then it may even have more volume then but the maximum allowable pressure differential will most likley be reduced because of the longer rotor length.

Many pneumatic conveying systems perform contrary to one's expectations.

Regards ■

Dear Mr JMDufour, hello Jack,

I am not sure about the displacement of the blower, because I used the educated guess of Jack.

If the blower is 10% longer (33”instead of 30”) then the displacement is 10% higher and the maximum pressure differential will be 10& lower.

Whether the motor is too small can be measured by an Amp-meter.

The load on the blower can be measured with a manometer.

Is the additional cooling for the drive motor or for the blower?

Is the blower clearance not too much, causing a low volumetric efficiency and thereby a higher outlet temperature rise?

If a pneumatic conveying system performs contrary to one’s expectation, the expectation is false. physics are always correct.

have a nice day.

teus ■

Can you measure the cylinderlength of the blower and the distance between th center of the main shaft and the secondary shaft?

teus ■

We rebuild 1033 Holmes blowers here in British Columbia, we have (2) cores in stock, both require rebuilding though

I can fax a performance chart if you email a fax number

Hank ■

please fax me one at 610-767-5241

thanks ■

1033 RBST 8/9/4 6 psi 5700 cfm 192 bhp at 1430 rpm

4 psi 5900 cfm 128bhp at 1150 rpm

4.52 Cubic Feet/ Rev 8 PSIG max 190 HP max

(I have seen 200HP and 250HP with jackshaft drives)

Last chart Holmes made shows 1500 rpm max, with 5920 cfm and 243 hp max, friction torque factor 0.913

These RBST blowers became obsolete in 1980, still lots of sawmills in Canada running them today, we rebuild 1 or 2 10x33's per year, we rebuild 50 or so blowers per year.

We work almost entirely for the forest industry across Canada and now into the USA, blowing chips, sawdust, fines, drywaste, sanderdust, hog, shavings, etc.

Hank Baum ■

dear Hank,

5700 cfm at 1430 rpm gives 3.986 cf/rev # volumetric efficiency 3.986/4.52 = 0.882

5900 cfm at 1150 rpm gives 5.13 cf/rev # efficiency 5.13/4.52 = 1.135 ?????

The cf/rev figure should be almost the same (pressure dependant), but certainly below the given value of 4.52 cf/rev

The performance data for 1150 rpm should be approx.

Volumetric efficiency 1 - (1-0.882)*1430/1150= 0.853 (volumetric is lower, because of lower rpm)

Delivered volume at 1150 rpm = 1150 * 4.52 * 0.853 = 4434 cfm

Delivered volume at 1170 rpm = 1170 * 4.52 * 0.853 = 4511 cfm

Compared to Jack's value of 4625 cfm, this figure is 2.5 % off.

Based on the information from Jack, I found a blower volume of 134.3 dm3/rev instead of the 128 dm3/rev (4.52 cf/rev)

That means that the calculations, I made, have an accuracy of approx. 95%

have a nice day

teus ■

Teus, you are correct, 1150 rpm 4psi gives 4650cfm requiring 102bhp, and for the rpm of 1430 at 4 psi the blower delivers 5900 cfm requiring 128 bhp. I had my numbers crossed ■