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REFERENCE
TOTAL HEAD
GUIDELINES FOR SIZING
Total Head is a combination of two components — static head and friction head — and is expressed in feet (refer to Typical Installation illustration, Figure 3).
Static Head is the actual vertical distance measured from the minimum water level in the basin to the highest point in the discharge piping.
Friction Head is the additional head created in the discharge system due to resistance to flow within its components. All straight pipe, fittings, valves, etc. have
a friction factor which must be considered. These friction factors are converted to, and expressed as, equivalent feet of straight pipe, which can then be totaled
and translated to friction head depending on the flow and pipe size. Basically, this is reduced to four steps.
1. It will be necessary to determine the discharge pipe size. In order to ensure sucient fluid velocity to carry solids, (generally accepted to be 2 ft per second),
flows should be at least:
• 9 gpm through 1-1/4" pipe
• 13 gpm through 1-1/2" pipe
• 21 gpm through 2" pipe
• 30 gpm through 2-1/2" pipe
• 46 gpm through 3" pipe
2. The length of the discharge piping is measured from the discharge opening of the pump to the point of final discharge, following all contours and bends.
3. To determine the equivalent length of discharge piping represented by the various fittings and valves, refer to Figure 5 and total all values. Add this to the
measured length of discharge pipe and divide by 100 to determine the number of 100 ft increments.
4. Refer to Figure 4 and find the required Pump Capacity (determined from Figure 2). Follow gallons per minute to pipe size being used. Multiply this number by
the number of 100 ft increments.
Add the Static Head and Friction Head to determine Total Head.
Plastic Pipe: Friction Loss (in feet of head) per 100 ft
Req'd Pump
Capacity GPM
1-1/4" 1-1/2" 2" 2-1/2" 3" 4"
1
2 .10
3 .21 .10
4 .35 .16
5 .51 .24
6 .71 .33 .10
8 1.19 .55 .17
10 1.78 .83 .25 .11
15 3.75 1.74 .52 .22
20 6.39 2.94 .86 .36 .13
25 9.71 4.44 1.29 .54 .19
30 13.62 6.26 1.81 .75 .26
35 18.17 837 2.42 1.00 .35 .09
40 23.55 10.70 3.11 1.28 .44 .12
45 29.44 13.46 3.84 1.54 .55 .15
50 16.45 4.67 1.93 .66 .17
60 23.48 6.60 2.71 .93 .25
70 8.83 3.66 1.24 .33
80 11.43 4.67 1.58 .41
90 14.26 5.82 1.98 .52
100 7.11 2.42 .63
125 10.83 3.80 .95
150 5.15 1.33
175 6.90 1.78
200 8.90 2.27
250 3.36
300 4.85
350 6.53
FIGURE 4
Friction Factors for Pipe Fittings
In Terms of Equivalent Feet of Straight Pipe
Nominal Pipe
Size
90° Elbow 45° Elbow
Tee (Through
Flow)
Tee (Branch
Flow)
Swing
Check
Valve
Gate Valve
1-1/4 3.5 1.8 2.3 6.9 11.5 0.9
1-1/2 4.0 2.2 2.7 8.1 13.4 1.1
2 5.2 2.8 3.5 10.3 17.2 1.4
2-1/2 6.2 3.3 4.1 12.3 20.3 1.7
3 7.7 4.1 5.1 15.3 25.5 2.0
FIGURE 5
Total Head Required
(A) STATIC HEAD
(B) TOTAL LENGTH OF PIPING
(C) TOTAL FRICTION FACTORS OF FITTINGS
(D) TOTAL (B+C)
(E) DIVIDED (D) BY 100
(F) HEAD LOSS PER 100 FT. OF PIPE (from Figure 4)
(G) FRICTION HEAD (ExF)
(H) TOTAL HEAD (A+G)
103