Greenheck Fan 240XP-CUb manual Belt Drive Selection, Cfm

Reading Performance Charts

The most important part of selecting a fan is the ability to read the performance charts. Most of the performance charts in the catalog are similar and are read in the same manner. Models RSF and BCF are

exceptions to this rule. The selection procedure for these models is handled separately. Direct drive and belt drive fans are also addressed separately.

Belt Drive Selection

Assume that a job requires a belt drive roof exhauster to move 1000 cfm against 0.25 in. Ps. Refer to the performance model at the bottom of this page. Start at the top of the chart with the 0.25 in. Ps column. (All numbers in this column correspond to .25 in. Ps.) Now follow the column downward until a value is found that slightly exceeds 1000 cfm. In this case, 1012 cfm is the first box that meets the requirements.

Note: Notice that each performance box is divided into 3 smaller boxes. The numbers refer to cfm, Sones and Bhp.

Example:

CFM			1012
Sone	Bhp	11.1		0.16

At this performance point, the sone value is 11.1 and the fan Bhp required is 0.16. Now by following the row to the left, we can determine fan rpm and fan model. In this case, the fan rpm is 1510 and the model is GB-090-4 which has a 1/4 hp motor.

Notice that the GB-090-4 is not the only model to choose from. If we follow the 0.250 in. Ps column down further, we find a performance point at 1010 cfm.

Table 2

At this point, the sone value is 7.9 and the Bhp is 0.14. Following across to the left we find the rpm to be 1355. The model is GB-101-4-R1, which also has a 1/4 hp motor.

Both the GB-090-4 and the GB-101-4-R1 will perform the air movement task equally as well. However, the sound generated by the fan may have to be considered. Compare the sone values: 7.9 sones for the GB-101 and 11.1 for the GB-090. The GB-101 is about 30% quieter. Where a low sound fan is required, the GB-101 would be a better selection. If loudness is not a factor, the GB-090 would be a better selection because it is less expensive.

Another possibility for this particular selection is a GB-100-4-R2. Even though there is no performance box showing close to 1000 cfm, there are two performance boxes that bracket 1000 cfm. At 921 cfm the fan will be running at 1260 rpm. At 1269 cfm the fan will be running at 1635 rpm. Therefore, there is an rpm for this model that will correspond to 1000 cfm (obviously somewhere within the 1260-1635 rpm range). As with all Greenheck belt drive fans, intermediate cfm values are easily achieved by adjusting the motor pulley (see illustration on next page).

MODEL										STATIC PRESSURE / CAPACITY
	hp	RPM	TS	0.000		0.125		0.250		0.375		0.500		0.625		0.750		0.875		1.000
(rpm RANGE)
				Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp	Sone	Bhp
		1360	3983	1030		957		884		807		725		632
				10.1	0.11	9.9	0.12	9.6	0.12	9.3	0.12	8.8	0.13	8.5	0.13
GB-090-4	1/4	1510	4422	1144		1078		1012		946		875		800		720		607
(1290-1710)				11.4	0.15	11.2	0.16	11.1	0.16	10.7	0.17	10.4	0.17	10.0	0.17	9.8	0.17	9.5	0.17
		1710	5008	1295		1237		1179		1121		1061		999		934		866		785
				13.4	0.22	13.3	0.23	13.2	0.23	13.0	0.24	12.7	0.24	12.4	0.25	12.1	0.25	11.8	0.25	11.6	0.25
		1070	3116	906		818		731		607
GB-101-4-R1	1/4			6.0	0.060	5.4	0.065	5.0	0.070	4.3	0.070
(1020-1400)		1355	3946	1148		1077		1010		943		856		739
				8.5	0.12	8.1	0.13	7.9	0.14	7.8	0.14	7.2	0.14	6.8	0.14
		1260	3669	1067		991		921		840		735		385
GB-101-4-R2	1/4			7.6	0.099	7.1	0.104	6.8	0.112	6.5	0.115	5.9	0.115	4.4	0.083
(1260-1635)		1635	4761	1385		1325		1269		1214		1161		1094		1019		928		792
				11.1	0.22	10.8	0.22	10.4	0.23	10.2	0.24	9.8	0.25	9.3	0.25	8.9	0.25	8.4	0.25	7.8	0.24
GB-101-3	1/3	1800	5242	1525		1471		1418		1367		1320		1270		1208		1141		1064
				13.2	0.29	12.8	0.30	12.5	0.30	12.3	0.31	12.2	0.33	11.3	0.33	10.8	0.33	10.6	0.33	10.1	0.33

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