Pipe slope is a critical element in reducing water collection following a sprinkler system drain. Water removal is important in that the largest detriment to sprinkler system life, corrosion, occurs across interfaces between air and water.
In this case the project is just a basic wet pipe sprinkler system. Wet pipe system piping is permitted to be installed level. Only dry pipe and preaction system piping is required to be pitched to drain and tie-in drains on dry pipe and preaction systems shall be pitched as well.
This requires sprinklers to be positioned away from obstructions a minimum or three times the maximum dimension of the obstruction.
NFPA 13 8.16.2.3 provides direction on how much slope is required for dry pipe installations: ¼ in. per 10 linear feet of pipe for mains and ½ in. per 10 linear feet for branch lines.
Yes, there is a criteria for min. slopes in water supply, espacially for transmission mains(under Pressure). The idea is to facilitate entraped air to be released from air valves and to drain the pipe at washouts, if necessary. Normally, 1:250 against the flow direction and 1:500 with the flow direction.
Using a minimum slope of 2% will encourage a good flow when directing water to a rain garden. For a 2% slope your pipe height will lower ~¼ inch for every foot of length. You can also approximate this by multiplying the pipe length in inches by . 02.
A slope that's too steep can cause water to flow too quickly, leaving solids behind, which can eventually result in a drain pipe blockage.
For drainage purposes, the current building codes require a minimum two percent slope or a one-fourth unit vertical for every 12 units horizontal. In other words, the roof must slope one-fourth of an inch for every 12 inches. The slope is barely noticeable to the naked eye.
Class 200 pipe, the most common class pipe used in irrigation, is rated for 200 pounds per square inch pressure (psi) and has a wall thickness of . 063” for a 1” pipe.
Disadvantages of using dry pipe fire sprinkler systems include: Increased complexity - Dry pipe systems require additional control equipment and air pressure supply components which increases system complexity. Without proper maintenance this equipment may be less reliable than a comparable wet pipe system.
1-2-3-2-1 watering technique:
In April water 1 day/week. In May ramp up to 2 times/week. In the heat of the summer water 3 times/week. In September drop back to 2 times/week. In the fall drop back down to 1/week.
We recommend that you use 40 psi when designing your system. Example: if your sprinkler heads use 2.5 gpm @ 40 psi, then a ¾” service (20 gpm) could operate approximately 8 heads at one time. Based on this example calculation, you would not have more than 8 heads on at one time.
Nothing should be in that area between the bottom of the sprinkler heads and the imaginary horizontal plane parallel to the ceiling that is 18 inches below. This is done to allow an even and unobstructed spray pattern from the sprinklers when triggered to extinguish the fire.
Dig for Your Sprinkler System
The trenches will be relatively shallow, usually 6 to 12 inches deep, depending on your area's freeze cycles and frost severity. The trench must also be deep enough to allow the sprinklers to retract underground to prevent breakage from lawn machines.
The spray of each sprinkler head is actually intended to overlap in order to ensure you never get a dry spot.
Canal banks - These generally have a slope of 1:1.5. However this ratio is usually increased to 1:2 with sandy soils and decreased to 1:1 with clay soils. Velocities greater than these should be avoided if erosion is to be prevented.
Consider the capacity of your irrigation system and the potential for future expansion. If you anticipate the need to add more sprinklers or increase the water flow in the future, opting for a larger pipe size like 1" can accommodate potential growth and prevent the need for costly modifications down the line.
Gradients from 1 in 40 to 1 in 110 will normally give adequate flow velocities. If the gradient is steeper than 1 in 40, the liquid may run faster than the solids in the sloping foul water pipe.
The steeper the slope and the less rapid the water infiltration rate, the more rapid the water runoff rate for a given soil.
Regardless of surface characteristics, when it comes to surface drainage, slope is the most important issue to consider. For efficient drainage, paved surfaces should have a minimum 1-percent slope. Turf or landscaped areas should have a minimum slope of 2 percent.
The ideal slope of any drain line is ¼ inch per foot of pipe. In other words, for every foot the pipe travels horizontally, it should be dropping ¼ inch vertically.
Corrosion plays a significant role in water main failures, but soil-pipe interactions, manufacturing techniques and human error are also important factors.
As a general rule, the recommended slope for most plumbing pipes is 1/4 inch vertical drop over every 1 horizontal foot, or about 2 percent.