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Wednesday, October 10th 2018, 9:19am

How to decide between PGP Ultra and MP Rotator?

Hello everybody,

this is my first posting. If my question has already been answered, sorry - I looked through this forum up to about 2012, but did not find any answer.

I own a house with about 5,600sqft. of lawn. The main area is roughly 80x70 ft, a secondary area is smaller.

I want to irrigate the lawn in 2019, and plan to use Hunter equipment, either PGP Ultra or MP Rotators.

I finished a plan with MP Rotators, mostly MP 2000-variety, and will start with 3 circuits, each needs about 9gpm. The well provides double the water, but with 2 circuits at 14GPM I won't get 40 PSI at all rotator heads.

I had a look at the PGP Ultra rotors, and it seems that since they give good coverage at 30 PSI, I could simplify my layout to 2 circuits of 14GPM, resulting in less irrigation time and less power consumption.

Pro Rotator:

- Hunter offers a planning guide for beginners, calculations and layout are not that hard even for a novice.

Con Rotator:

- I read some reports that there are issues with even coverage at the edges of the pitch circle, the range of the beam at the edges is shorter than in the middle. I have no idea how much this affects even coverage in a head-to-head-setup.
- If a head's range turns out to be too low, I need to exchange the whole sprinkler head (cost).

Pro PGP Ultra:

- A bit cheaper (at least in Germany)
- Changing a head's range is easy by changing the nozzle, no need to buy a new head
- Just one kind of head for all requirements, buying some extra nozzles is quite cheap

Con PGP Ultra:

- No planning guide supplied by Hunter for beginners
- Choosing between the many nozzle colours is not easy for beginners
- For small details, there are no special heads like the MP corner or MP strip

How would you chose between these technologies? What are your reasons for preferring one of these over the over?

Best regards,

Detlev

Wet_Boots

Supreme Member

Posts: 5,287

Location: Metro NYC

2

Wednesday, October 10th 2018, 10:06am

the key word here is "well" - this means two things

first, the water may have particles of sand and will need filtering - a Vu-Flow is a filtering standard (size shown fits your stated well performance)

second, the well output needs to be completely employed by the sprinkler zone - this is where the PGP is the superior choice, because of the interchangeable nozzles

as an aside, do not overlook the plain old original PGP rotor - it has the widest range of nozzles, more than the Ultra series, and that can make a difference when it comes to tweaking zone performance

3

Wednesday, October 10th 2018, 3:14pm

First of all, thanks for your very fast answer!

About filtering: Of course, I am aware of this. The well is already equipped with an Irritec Y-Filter, and a 120-mesh disk cartridge. The well is still very new and not yet sand-free. i estimate it os currently down to about 0.17 ounces (5g) per 1000l, which is not much but enough to keep cleaning the filter once a week. The well is oversized and exceeds the pump's max capacity of 22GPM.

Sorry, I am not a native english speaker and don't get the meaning of employ in this context. The pump works at good efficiency between 8 and 15 GPM, and the controller can handle anything from 2GPM up. Based on testing, I have confidence about 40psi after laterals for 9GPM.

Wet_Boots

Supreme Member

Posts: 5,287

Location: Metro NYC

4

Thursday, October 11th 2018, 1:57pm

........ and the controller can handle anything from 2GPM up....
You did not mention a pump controller. They still aren't standard equipment on every well. Systems in the past had to exactly match the output of well and pump, without any controller or other aids, so that the pump would not cycle on and off. That's where the original PGP series worked better than anything else, because of the range of nozzle sizes.

5

Thursday, October 11th 2018, 3:29pm

Ah, ok. It's a submersible pump that is optimised for 3000l/h, but I use an electronic switchbox. They don't switch off at a specific pressure, only when throughput falls below a threshold. it turns on if pressure falls below 20 PSI and turns off when there is less than about 2gpm throughput for 15s. So if I use only 5 or 10GPM, the well keeps running. These switches aren't expensive, the only drawback: At low throughput, the pump runs at a high pressure, stressing the laterals and the filter if the pump is way too strong.

i believe I may find a very good setup with PGP Ultra and the MPR-nozzles. The flexibility seems very good, where a MP Rotator doesn't have enough range, I need to change the whole unit. With PGP or PGP Ultra, it's a cheap Nozzle.

Thanks for your advice :)

Wet_Boots

Supreme Member

Posts: 5,287

Location: Metro NYC

6

Thursday, October 11th 2018, 6:00pm

Well controllers aren't supposed to stress the sprinkler system. They will subject the pump and its drop pipe to higher pressures, but that's the price you pay for that 'controlled' output, and possible savings by not needing a larger pressure tank.

7

Friday, October 12th 2018, 2:10am

Actually, with these controllers it's recommended not to use a pressure tank at all. When the valves shut, the pressure rises up to the maximum value pretty fast, but after about 15s, the pump is turned off.

If the system is properly sealed, the remaining pressure is higher, but the main line and the filters must have a higher rating anyway.

Mechanical controllers:

Pump is turned on when the pressure is below minimum
Pump is turned off when the pressure is above maximum

Result: Cycling if the system does not use much water, but the maximum pressure is user-selected

Electronic controllers:

Pump is turned on when the pressure is below minimum (usually 20 PSI)
Pump is turned off when there is no flow for 15s

Result: No cycling even if there is low water consumption, but with low flow or no flow, the pressure is closer to the maximum the pump can generate. This can be an issue if pumps have a very steep pressure curve.

For an example, look at the higher-performing pumps in this chart:



My pump is 10m=30 feet down, and the 3,5 SDM 3/18, while giving amazing pressure at 13GPM (3 m³/h), would push 10 Bar= 140 PSI into the filter and main line when the valve closes. ATM, I use a 3/11, and the plumbing would be sufficient for a 3/15 if I need more pressure. With the 3/18 and an electronic controller, stand-by pressure would equal the manufacturer's maximum rating. With a mechanical controller and a pressure tank, this would be easier to manage. I believe that's why mechanical controllers are still around. The price difference is not much.

But that's disgressing from the main topic:

It seems that with PGP Ultra, I get rotors which are more flexible than the MP Rotator, and if I make minor mistakes in my layout, they are easier to adjust because the nozzles are more flexible. If that's correct, I will use the PGP Ultra rotors.

This post has been edited 6 times, last edit by "top_gun_de" (Oct 12th 2018, 3:27am)


Wet_Boots

Supreme Member

Posts: 5,287

Location: Metro NYC

8

Friday, October 12th 2018, 6:52am

Thanks for the controller info. The earliest of these things were purely mechanical, and built around a pressure reducing valve. The water supply would still have a pressure tank and a pressure switch, but the tank was just a mini, to pair with a pressure switch. The specialty valve would hold output operating pressure to a set point, and once the sprinkler system stops operation, the internal bypass allowed a small flow to operate the pressure switch. The higher pressure resulting from a low flow remains upstream of the valve.

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