Vintage Garden Syringe Sprayers    

Back Double Action Sprayers - How They Work

Valve A

Valve B

First priming pull strokes (after a few strokes to remove air).  Inner tube is being pulled out (extending). Valve A is closed. Valve B is open. Liquid is sucked from container into larger tube.    

Priming complete.  Inner tube is pulled out (fully extended).

Push stroke.  Inner tube is being pushed into outer tube. Valve A is open. Valve B is closed. Liquid passes through valve A filling front of large tube and also passing into the inner  tube.    

Push stroke complete.  Inner tube is pushed fully into outer tube.  

Pull stroke.  Inner tube is being pulled out (extends). Valve A is closed. Valve B is open. Liquid is sucked into larger tube. Liquid already in front of valve A in the outer tube is forced through the hole in the inner tube. This expels the liquid already in the inner tube out through the lance and nozzle.

Valve A

Valve A

Valve A

Valve B

Valve B

Valve B

Pull stroke complete.  Inner tube is fully pulled out (fully extended). Main and inner tube are both full.  

Valve A

Valve A

Valve B

Push stroke.  Inner tube is being pushed into outer tube. Liquid (blue) passes through valve A. This forces liquid through the inner tube and out through the lance and nozzle. Some sprayers have a pressure chamber which assist in providing a continuous spray.  

Valve A

Valve B

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The picture on the left shows the main valve and piston which is on the end of the inner tube. The leather washer provides the seal between the inner and outer tubes. The centre picture shows the inside of the valve when it is closed. The flow is blocked so that the end of the inner tube acts as a piston, sucking in liquid from the container and at the same time expelling liquid via the lance and nozzle. The picture on the right shows the flow when the valve is open. Liquid flows around the ball and both into the inner and outer tubes. Liquid going into the inner tube expels liquid already in the inner tube/lance out through the nozzle. The ball is held in by a brass pin which passes through the inner tube (end marked with red spot). (Note - the ball would normally be brass, but has been substituted in the photograph for a stainless steel ball so that its shows in the picture).