An Overview of Injection Valves: Quills vs Lances

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An Overview of Injection Valves: Quills vs Lances

Why Should You Use Injection Valves
For Chemical Feed Systems 

Injection valves are designed to ensure a chemical feed system injects directly into the centre of the process stream; ensuring efficient mixing and preventing corrosion along the inside of the process pipe.

Alternative methods such as a threaded tap, place unnecessary strain on the pipework joint; pooling of the concentrated chemical can then occur jeopardising the structural integrity of the threaded joints. Utilising an injection valve prevents this issue by introducing the chemical into the centre of the flow allowing for even distribution.

There are two common variations of injection valves – a quill and a lance.


Read on or watch our video to find out the key differences.  

Injection Valve (Quill)

How it works: 

Using an integral check valve, an injection quill does not allow the process fluid to enter or travel up the injection line; keeping both liquids separated at the mating interface.

Materials available: 

  • PVC
  • PVDF
  • Stainless Steel

Application decision 

This is the simplest method of introducing a chemical into the main flow stream, however the process line must be depressurised and drained for maintenance.

Use these on small systems where the process main can be easily isolated.

Injection Quill_blog

Withdrawable Injection Lance
(Corporation Stop)

 

How it works: 

Withdrawable injection lances are similar to injection valves with the added benefit of being able to be removed without turning off the process flow.

Using a radial seal, the lance can be retracted while sealed until it reaches a point at which a shut-off valve (typically a ball/cone valve) can be closed; the lance can then be safely removed without leakage.

A locking mechanism combined with a hard stopping point (via chain or cable) ensures the lance does not slide all the way out under system pressure or during servicing.

Materials available: 

  • PVC
  • Stainless Steel

Application decision 

Use these on systems where the process main cannot be easily isolated or shut down.

Injection Valves Common Questions

 

Q) Why do injection quills have a 45 degree chamfer at the end? 

  • So that all media injection is caught in the flow. 

Q) Which way does the chamfer face in the line?

  • Toward the flow to prevent backflow and chemical residue in the quill/lance.

Q) What is the purpose of a ball valve on the withdrawable quill?

  • To shut off the lance from the mainline for ease-of-removal during maintenance and servicing

Q) What is the benefit of having the injection valve sit in the centre of the flow?

  • To prevent the injected chemicals from channeling down the pipe wall causing corrosion of the inside of the pipe.

PAAS is proud to distribute injection valves from the USA Manufacturer, Griffco. 

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