Tuesday, August 1, 2017

Fence Paint Equipment


I’m very often asked about fence paint equipment.  I will try and break down the different types and classes of machines and where they may help in ag painting.  Below I have listed the major different types of paint machines.  Below the list I will cover the advantages and disadvantages of each variation 
Electric versus gasoline powered
Diaphragm versus piston fluid unit
Clutched versus Hydraulic
Fast versus slow stroking machines
The first choice that will need to be made is whether the fence paint machine needs to be gasoline powered or will electric work on your job.  Electric is a significant cost savings, however you will be tied to either extension cords or generators.  Many customers comment that they already own a generator so that is not a consideration to them.  That’s great but remember painting fence is a very dirty job and there will be stray paint.  Don’t fall in the trap of saving on the electric paint sprayer only to destroy your very nice generator.  The other deterrent to electric is output.  Almost all electric machines are meant to be plugged into the standard wall socket.  These sockets are normally protected with 15 or 20 amp breakers.  This is the limiting factor for painting output.   Electric machines can work on fence paint jobs, however they will almost always be somewhat under powered. 
The reason that electric machines are cheaper is obviously the cost of a gas engine is greater than an electric motor.  This is magnified by the fact that electric motors can be controlled be relatively cheap electronics while a gasoline engine needs either a clutching mechanism or hydraulics.  The reason is very simply, an electric motor can be turned off when the fluid pressure reaches the desired level.  Gasoline motors must run the entire time, therefore the motor must be disengaged by a clutching mechanism or hydraulic must allow for the hydraulic fluid to bypass the painting portion of the machine.  There are electric machine that use clutching mechanisms (the titan power twin series is an example), however most of the less costly electric machines do not have clutches.
The paint pumping portion of the machine (often called the fluid section) will be one of two primary types.  Diaphragm type pumps use an off centered rotating shaft to move a diaphragm in and out.  This pumping action along with two one way check valves produces the fluid movement.  The other type is a positive displacement piston type pump.  This type of pump also uses two one way check valves but the pumping action is accomplished by the up and down movement of a piston within a cylinder.  Piston type pumps are much more desirable for painting fence.  This comes along with a significant cost increase.  The reason pistons are more desirable than diaphragms is durability and output.  The diaphragms must be made out of a flexible rubber like material in order to continually flex back and forth.  This soft rubberlike material is prone to breaking.  Theses diaphragms can be replaced but they are relatively expensive and are messy to replace.  You also simply don’t see large machines that use diaphragms.  My opinion is that diaphragm type machines can be used on fence paint jobs but can tend to be undersized and much less reliable than piston type pumps.  You might want to consider this a one paint job use type pump.  It is a significant cost upgrade to go to a piston type pump but I would recommend you make the additional investment if either you have a large job or want the same machine to paint your fence multiple times.  Going forward in this blog, all the pump types we consider will be of the piston and gasoline type.
The next major step up in terms of quality and price is moving from a clutching type pump to a hydraulic machine.  I have included the specification pages out of the titan brochure, for reference, at the bottom of the blog.  The clutching type pumps would run from the advantage GPX33 to the advantage GPX220.  The only difference in these machines is output (gallons per minute).  The hydraulic pumps would run from the power twin 4900 plus to the power twin 12000DI plus.  There is a slight difference in the pressure of these pumps (insignificant for fence painting) and again the main difference is output in gallons per minute.  The last three pumps are the hydra series.  These pumps are what we refer to as slow strokers.  The advantage of a slow stroker is the wear factor.  A good rule of thumb is wear is proportional to the operating speed squared.  This means that if you double the speed of the pump, you will quadruple the wear factor.  This particular brochure does not list a specification called CPG or cycles per gallon.  The hydra pro IV’s CPG is 20 while the power twin 8900’s CPG is 40.  Put simply, the hydra pro IV will just purr along while the power twin 8900 is pumping hard.  If you look closely you will see both pumps are rated at 2.5 gallons per minute.   This CPG becomes very important to commercial contractors but is relatively insignificant to almost all individuals.  There is no need for any farm, no matter the size, to move to a slow stroking machine.  Slow stroking machines should only be considered by individuals who intend to do commercial contracting and even then many commercial contractors use fast stroking machines.
The practical difference between a clutching machine and a hydraulic machine is durability and reliability.  The pumping portion of these machines are identical.  Hydraulic machines will be more durable and reliable.  There is a price difference between these two classes of machines but it is not nearly as significant as the others we have discussed.  I personally prefer the hydraulic machine due to the reliability factor.
Output (gallons per minute, GPM) is critical in fence painting.  Pump output will determine if one or two painting guns can be operated simultaneously and how fast the job can be completed.  Larger GPM means bigger tips and the potential to use two guns.  Pump output will determine what tip size any particular pump can handle.  Larger tips mean faster painting speed and fewer potential tip clogs.  I will cover tips in more depth in a future blog.  It is absolutely critical that tips are sized correctly for the pump being used.  If a tip is sized too small for a particular pump it will slow the job down which is not ideal, but is not overly detrimental.  If on the other hand a tip is sized too large a condition I refer to as gapping will occur.  Gapping is when more paint can pass through the tip than the pump can pump.  When this condition occurs you get a significant drop in system pressure when the piston is reversing directions.  If this happens while you are painting you will notice the paint will spray hard then soft as the pump passes through its painting cycle.  When the job is completed, it may very well look just fine, but as the paint wears, you will increasingly notice the difference in paint thickness (your fence will begin to look like a zebra).  If you notice gapping, immediately go to a smaller tip size.
Here are some rules for pump output.  For a single gun setup, I would not want to drop below .5 GPM and I would really like to be at or above .75 GPM.  For a strong gun with good tip sizes I would want 1.0 GPM.  For commercial contractors, I would prefer over 1.25 GPM.  If you are considering a diaphragm, electric type pump, you can drop slightly below these levels but I don’t think you will be very happy and can have total failure. 
The decision to set up for one gun or two guns will revolve around everyone’s own personal situation.  Remember that these pumps will paint fence fast, even if one gun is used.  I would think that a one gun setup would be enough for all but the largest farms.  I would figure that a single person could paint about ½ mile of fence in an 8 hour day with a single gun.  I would also assume that two people could paint a mile of fence in 8 hours.  If a third person is added to the two gun setup, you will see an increase to over a mile per 8 hours.  Most commercial contractors want the ability to use two guns even if they do so only occasionally. 
We typically recommend the power twin 4900 for single gun operation, the 8900 for two gun operation and the hydra pro IV when a slow stroker is needed.  We see very little advantage to the 6900, 12,000 or hydra m 4000. 

Good Luck.

3 comments:

  1. Great layout for Fence painting equipment selection and education.

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  2. Thank you for sharing this interesting and informative article, painting with airless spray gun will be faster and more interesting!

    Air Spray Gun

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