Spray Rig Plumbing

Discussion in 'Pesticide & Herbicide Application' started by otis44, Nov 18, 2013.

  1. otis44

    otis44 LawnSite Member
    Messages: 104

    Over the winter I'm looking to put together a skid sprayer. I'm mainly into mowing, but I am planning on getting my license this winter and have a few accounts I can pick up with hopes of adding more. I'm looking to spray possibly some pre, but mainly post emergent on fescue lawns.

    I'm hoping to put together a 100-200 gallon system and looking to spray in the 1.5 to 3 gallon per minute range. I'm thinking a 6.5/gear reduction engine coupled to a roller pump w/300' 3/8 hose and a chem lawn type gun. At this point I can't justify the cost of a diaphragm and I am not sure I need the pressure anyway. My question(s) are in regards to the plumbing of the system. Below is what I have in mind, please offer any ideas of advice you have.

    3/4" from tank to strainer, 3/4" from strainer to pump, 3/4" line to 3/4" tee, 3/4" tee inlet, one leg of tee reduced to 1/2" back to tank with ball valve for bypass, other leg of tee 3/4" to pressure regulator, 3/4" pressure regulator inlet, regulator outlet reduced to 3/8" to hose reel.

    Again, any advice on this set up will be greatly appreciated.

    CHARLES CUE LawnSite Silver Member
    Messages: 2,451

  3. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,800

    You don't save much by building it yourself. Scroll down and click Gregson Clark--good people and a good guarantee. I suggest a 200 gallon tank, as you may need more capacity in the future; costs slightly more. No need to fill it to the top. And next year you may buy a 3/4 ton truck.
    Also you should have 3 tubes coming from your pressure regulator valve. Flow in, flow out, bypass out. The bypass flow can be combined with the agitation flow on the way back to the tank.
    I would suggest 1/2 inch hose going to the reel...less restriction.

    Remember that 3/8 hose reduces the flow in a major way; cuts it by about 55 percent, compared to half-inch. And the longer the hose--the more you lose by friction, maybe as much as 10 percent per hundred feet.
    I am thinking you will get about 1 gallon per minute. Once you begin to spray, your pressure at the gun will drop--perhaps below 50 lbs.
  4. otis44

    otis44 LawnSite Member
    Messages: 104

    Thanks for the replies, I had found some diagrams over on Dultmeir's site today. That plus the above information gives me something to chew on.

    I did not realize the difference in capacity between 1/2 vs. 3/8 hose. One of the pumps I am considering is an 8 roller hypro which states it is rated for 100psi continuous and @ 540rpm will put out 7-8 gpm. From what I can gather from some flow charts, 100psi @ the pump, coupled w/300' of 1/2" hose should yield somewhere in the neighborhood of 25-30 psi @ the gun and a flow capacity in the neighborhood of 2.5-4gpm. This should take into consideration additional restrictions in the plumbing system itself, before the fluid enters the hose. (Please correct me if I am wrong on this).

    The 3/8 hose at these pressures and lengths as you stated would be too low and too slow to even consider. These numbers make a diaphragm pump sound better all the time, but I am a small solo operator and am not sure how big the spraying side of the business will become, or how big I want it to become. I am confident I can pickup 6-10 accounts immediately next season and would probably be satisfied if I eventually had 25-30 in total.

    A question on another note in regards to the engine. In thinking in terms of upgrading down the road to say a Hypro D30. Will this pump (or similar) mate to an engine that is already gear reduced, or do you have to use the reduction box made by Hypro and mate it to a non-gear reduction engine?

    Thanks again for the help.
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,800

    Otis, I am thinking that one gallon per minute is fine for spraying weeds--assuming you have a gun and suitable nozzle which can deliver a filled cone-shaped pattern, so you can move the gun back and forth as you walk, covering 100 percent. You want to swing your arm so you cover about 7 or 8 feet wide, (and allow a bit of overlap). Water is only the carrier--let the chemistry do the work.

    If you plan to mix fertilizer with the liquid...you need at least 2.5 gals per minute to reduce the chance of fertilizer burn. So...apply the fert with a spreader for the time being.

    Roller pumps are inexpensive, but not suitable for all products. Wettable powders--probably not. Roundup--probably not.

    Remember the pump salesman will be a bit optimistic--they will quote the performance of a new pump under ideal conditions with zero restrictions--8 gpm, no problem. The more pressure you demand, the pump has to work harder and the less flow the pump can produce.

    Perhaps others will chime in on roller pumps and also whether or not 1 gallon per minute will be suitable for weed control. I am sure others use a similar setup for spraying--particularly when starting out.

    Not sure, I think the D-30 Hypro pump is available without the gear reduction. It is the type suitable for PTO drive at about 540 rpm.

    CTPTURF LawnSite Member
    Messages: 80

    I have a 300 gallon spray rig with a hypro d-30/5hp gas combo and 300 feet of 1/2" hose to a chemlawn gun. For me to get 3 gallons a minute, I have to run pump at 200psi and agitation valve halfway closed. I don't think a roller pump and 300 feet of 3/8 hose would be able to get there, especially if you wanted good agitation while you are spraying.

    Like others have said, if you are spraying liquid ferts, you need the greater volume.
  7. Cadzilla

    Cadzilla LawnSite Senior Member
    Messages: 903

    Use a piston pump. You couldn't pay me to use a diaphragm pump again. Ever.

    You'll thank me later.
  8. ted putnam

    ted putnam LawnSite Platinum Member
    Messages: 4,746

    I have a friend that used(and abused) a GNC industries piston pump for 10 or 11 yrs and never had to do anything to it. I bought one of their P-15 units that I use for my tree/shrub sprayer. Downside is that a piston pump costs more than a diaphragm pump. The upside is that your gear reduction is the proper sized pulleys. I had a 5 hp Honda so I just bought the P-15 pump/mounting plate,600psi regulator and their pulley set with cover/guard. It cost me around $1100 2 yrs ago. I expect many years of trouble free service out of it.

    Last year I bought a complete pump/motor unit from Sprayer Depot.com. The unit was a 5 hp Honda, Hypro D-30 pump with Hypro regulator and gear reduction for $1150. All I had to do was run hoses from it to a tank and hose reel. I thought it was such a great deal I actually bought 2 of them. I used one for a replacement on an old Lesco 200 gal unit(a 15 yr old unit) and I used the other to build a space saver unit for one of my pickups. You don't save a whole lot by building one yourself but you can save $500 or so. The D-30 is a great medium duty pump and unlike a roller pump would allow you to mix more abrasive materials without all the wear. I do replace the diaphragms annually in winter to save unexpected problems a couple of months into the next season though.
    Last edited: Nov 20, 2013
  9. Cadzilla

    Cadzilla LawnSite Senior Member
    Messages: 903

    Yeah all I use is the GNC pumps. I have a five year old P-10 unit thats never given me one issue. They make great spray units.
  10. otis44

    otis44 LawnSite Member
    Messages: 104

    Thanks for all the above advice. I decided to scrap the roller pump idea, and the piston pumps look good but seem to be out of my price range. I picked up a new Hypro D30 with regulator and gear reduction today and bought a Kohler Command 7hp engine. Don't know that I need 7hp, but for the price I decided to give it a try.

    I'm probably going to go with a manual reel to save a few bucks ( I know a 12 volt would be better), but there is quite a price difference. Any advice on spray hose (brand) is welcomed. I think I am going to go ahead and use 1/2 hose. I am going to try to source a tank here locally, a farm supply has a fair deal on them and will probably use Rittenhouse or similar for the incidental parts such as the strainer, gun, etc. Thanks again for the help.

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