Here are some tips to improve your spraying operation when applying finish to wood products.


1 How to eliminate distorted spray patterns — A plugged or worn tip can cause pattern surging. A worn tip, or too large a tip, can also cause a pulsating fluid delivery; change to a smaller tip or replace the worn one. Also, if too many guns or too large of tips are used, the pump may not have the capacity to support them.

2 Avoiding streaks in the spray pattern — Low pressure at the tip can lead to streaks in the spray pattern, particularly at the outside edge. To eliminate this, turn up the pressure control knob. However, if the sprayer is already at its maximum, try using a larger diameter hose or shorten the length of the hose to reduce the pressure drop. Also, make sure you are using the tip size rated for your gun.

3 How to properly size a pump — A pressure loss calculator tool can help determine the size of the pump needed at the beginning of the run, to get the pressure and flow rate at the dispense point. To calculate the flow rate, you’ll need to know: the fluid pressure at the dispense point, the dispense point orifice size or tip size (if used); and the fluid specific gravity or weight/gallon. To calculate the friction loss in the line, you’ll need to know: the fluid flow rate; hose/pipe length; hose/pipe inside diameter (ID); fluid viscosity in centipoise (CPS); fluid specific gravity; and vertical rise (if applicable).

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