telias wrote:Changed it over to a 7, still doesn't seem like 30-40 ft. Closer to 20 I'd say.

The screw is all the way up too, so there is no interference. Could it just be that I have horrible pressure?

If so, your pressure is abysmal. Like Andy said, I'd check that.

Also, do the bucket test. Mark a given gallon line on the bucket if yours doesn't have it (milk jugs are handy for measuring water amounts pretty well without going into hysterics about it). Say, five gallons.

Set the bucket under the spigot at full open. Measure how long it takes to hit the line (with the agitation, some estimation is required, and usually a few tries to get a good average).

Say it took you 50 seconds to get that 5 gallons. 5/50 = 1/10th of a gallon per second. Multiply by sixty. So 60 * 1/10 = 6 gallons per minute. That would be the absolute maximum flow to the sprinkler (minus the hose friction, of course).

Always keep your nozzle number low enough to stay under that output. The longer and smaller your hose is, the further under you'll need to go to maintain decent pressure. With 100 feet of 5/8" hose in the back, my maximum works out to about 4.8 gallons per minute or pressure drops too much.

Measure the PSI at the tap AND at the end of the hose, too. There could be a big difference.

Michael Wise wrote:

andy10917 wrote:Measure the PSI at the tap AND at the end of the hose, too. There could be a big difference.

Really? Given the same elevation, I thought static pressure was static pressure. Its when the water starts moving that pressure losses come into play.

Static pressure will be static pressure.

If you can measure it under flow, you might notice a big difference if something's stuck in the hose, though.

I eventually had to have a plumber out. At installation, my front hose bib had a bit of solder stuck in the line, enough to seriously reduce water pressure under flow. I couldn't find it, and didn't have the equipment to work with it. It took him ten minutes.

That's in a perfect world. The reality is that I've seen many, many hoses and connectors that say 5/8", 3/4", 1", etc., but the fittings/connectors throttle the water passing through them down to as low as 1/4". Pressure downstream of that point, even if the hose itself is wider, is reduced. When I built my system, I went with all 1" supply lines and a 1-1/4" manifold to make sure that I wouldn't have serious losses along the supply line. The cost of larger supply lines is not much in the scheme of things.

Use this example (which is greatly exaggerated for illustration): picture two sewer pipes connected to each other by a straw. The pressure will be equal if no water is taken from the downstream one. But as soon as any water is taken from the downstream one in excess of the ability of the straw to replace the water, the pressure will drop rapidly.

You're right. It won't work with a screw-on pressure meter. An in-line one would be needed.

You'll have to measure flow at the tap, and flow at the end of the hose. If they are very different, there is a restriction somewhere.

The pressure will be equal if no water is taken from the downstream one.

You're both saying the same thing. Under flow, the hose pipes connected by the straw will differ in pressure. Static water pressure will be identical across the system, however, assuming the altitude is the same.

You'd have to measure under flow. Sometimes you can get a good clue from flow rate. If the bucket test above fills fast at the spigot and considerably slower at the hose end, something is awry in the hose.