You are here

What Are The Main Differences Between A Solo Piston Pump And A Solo Diaphragm Pump Backpack Sprayer?

Solo backpack sprayers are made in Germany and are available with a piston pump or a diaphragm pump.

In Germany the most popular type of backpack sprayer is one with a pison pump.

So, should I buy a Solo backpack sprayer with a piston pump or a diaphragm pump?

It would be wrong to call one pump better than the other. It really depends on the intended use for the sprayer.

You can generate more pressure with a piston pump

The piston pump is capable of generating a maximum pressure of 6 bar. The maximum pressure that can be produced with the diaphragm pump is 4 bar. Higher pressure produces smaller droplets and has a further reach. This is ideal if you want to spray insecticide on trees and larger shrubs. It is not so good if you are spraying weedkiller on your drive because the finer droplets are more likely to drift in the wind.

The piston pump is easier to replace or repair

Only 2 screws have to be removed to access the piston pump. A total of 12 screws have to be removed to access the diaphragm pump. A piston pump is more physically robust than a diaphragm pump.

The diaphragm pump is a completely closed system and is more chemically resistant

If you are spraying corrosive, ‘gritty’ or more ‘syrupy’ liquids (e.g. liquids made of a mixture of insoluble powder and water or liquids with a high viscosity) then you need a diaphragm pump.

In conclusion

As a rule of thumb: if you spray down, use the diaphragm pump it has a lower pressure with less drift and is good for weed killing. If you spray up, especially with a spray lance extension, use the piston pump, it has a higher pressure and produces smaller droplets, giving better coverage and canopy penetration.

Criteria Piston Pump Diaphragm Pump
Solo Model 425, 435, 473P 475, 485, 473D
Pressure Up to 6 bar with the plug on top of the preassure chamber. Without the plug up to 4 bar
Note: this does not apply to the 473P model as a plug is not supplied with it
Up to 4 bar
Note: More effort is required to generate pressure above 3 bar
Handling Higher Pressure is easier to obtain Higher pressure is difficult to achive with pump lever.
Spray Liquid Use with low abrasive low viscosity spray liquid Use with more abrasive and more aggressive liquids, also with higher viscosity liquids
Seals Viton seals Herchlor seals
Resistance More resistant mechanically More chemically resistant
Reach and Output Volume More reach because of higher pressure Reduced reach because of lower pressure


View our whole range of backpack sprayers. To find our more about Solo backpack sprayers then read our article Frequently Asked Questions Regarding Solo Backpack Sprayers.


flower1_0.jpgWould you like to receive regular news, tips, ideas and promotional codes from Gardenlines?flower2_0.jpg

flower1_1.jpgSign up here for our newsletter and join the Gardenlines Clubflower2.jpg