NAC445A.969. Pressure distribution system.

     1. A pressure distribution system may be used in conjunction with any effluent absorption system that uses distribution pipes. A pump must be used to pressurize the pressure distribution system.

     2. The active dosing volume of a pressure distribution system must be approximately 10 times the total volume of the distribution pipe used in the effluent absorption system.

     3. A solid delivery pipe which connects the dosing tank to the perforated distribution piping must be placed below the frost line. The delivery pipe must maintain a downward slope from the distribution lines to the dosing tank to ensure drainage between discharges. The use of check valves and other devices that prevent backflow to the pump is prohibited.

     4. To reduce the potential for plugging and clogging of distribution pipes, the diameter of the discharge hole must be at least 3/8 inch. If an effluent screen is used, the diameter of the discharge hole may be reduced accordingly. The rate of discharge for various-sized holes at various pressures are set forth in the following table:

DISCHARGE RATES AT VARIOUS PRESSURES (gallons per minute)
Pressure		Hole Diameter
Per Foot of Water	Per Square Inch	3/8 Inch	7/16 Inch	1/2 Inch
1	0.43	1.66	2.26	2.95
2	0.87	2.34	3.19	4.17
3	1.30	2.87	3.91	5.10
4	1.73	3.31	4.51	5.89
5	2.17	3.71	5.04	6.59

     5. Friction losses in schedule 40 plastic pipe are listed in the following table:

FRICTION LOSS IN SCHEDULE 40 PLASTIC PIPE; C = 150 (ft per 100 ft)
	Pipe Diameter (inches)
Flow in gallons per minute	1	1 1/4	1 1/2	2	3	4	6	8	10
1	0.07
2	0.28	0.07
3	0.60	0.16	0.07
4	1.01	0.25	0.12
5	1.52	0.39	0.18
6	2.14	0.55	0.25	0.07
7	2.89	0.76	0.36	0.10
8	3.63	0.97	0.46	0.14
9	4.57	1.21	0.58	0.17
10	5.50	1.46	0.70	0.21
11		1.77	0.84	0.25
12		2.09	1.01	0.30
13		2.42	1.17	0.35
14		2.74	1.33	0.39
15		3.06	1.45	0.44	0.07
16		3.49	1.65	0.50	0.08
17		3.93	1.86	0.56	0.09
18		4.37	2.07	0.62	0.10
19		4.81	2.28	0.68	0.11
20-24		5.23	2.46	0.74	0.12
25-29			3.75	1.10	0.16
30-34			5.22	1.54	0.23
35-39				2.05	0.30	0.07
40-44				2.62	0.39	0.09
45-49				3.27	0.48	0.12
50-59				3.98	0.58	0.16
60-69					0.81	0.21
70-79					1.08	0.28
80-89					1.38	0.37
90-99					1.73	0.46
100-149					2.09	0.55	0.07
150-199						1.17	0.16
200-249							0.28	0.07
250-299							0.41	0.11
300-349							0.58	0.16
350-399							0.78	0.20	0.07
400-449							0.99	0.26	0.09
450-499							1.22	0.32	0.11
500-599								0.38	0.14
600-699								0.54	0.18
700-799								0.72	0.24
800-899									0.32
900-999									0.38
1000 or more									0.46

     6. Distribution pipes in the pressure distribution system must be looped.

     7. Lateral distribution pipes must be spaced so that they are not less than 4 feet or more than 6 feet apart. The outside laterals must be placed at a distance from the perimeter of the absorption area that is equal to one-half of the distance between the lateral distribution pipes.

     8. Manifold diameters for various manifold lengths, number of laterals and lateral discharge rates for plastic pipe are shown in the following diagram:

     9. The required lateral pipe diameters for various hole diameters, hole spacings and lateral lengths for plastic pipe are shown in the following diagram:

     (Added to NAC by Environmental Comm’n by R194-07, eff. 8-26-2008)