Custom poppet valve redesign help needed

[hollerg]

I have a spring loaded adjustable differential poppet valve that is too small, and the vendor does not make a larger one.

It is a special configuration that places the poppet port at the outlet barrel tip. The valve body has an extended barrel to extend the port down to the bottom of the threaded mount to match up with the inner wall of a cavity.

I need a redesign to maintain the functionality of the valve while enlarging the orifice to pass 50% greater flow. Pushing the flow rate causes erosion. Referrals to firms capable of the redesign would be appreciated.

 

[BillBirch]

Do you have a sketch?

 

[israelkk]

Increasing the flow rate will need the increase of the orifice diameter. This will create the need to increase the spring load and the poppet travel. The result maybe a larger spring that maybe too large to fit inside the current space in the valve. As BillBirth wrote without seeing a cross section of the valve it will be difficult to further comment on this post.

 

[hollerg]

Attached are the drawings that show the current design (0.067 inch orifice opening), the original valve w/ 0.046 orifice flow curve for water, and the location of the damage. The

I actually have two feed systems which feed the cavity. The smaller flow has even wear over a 2-3 yrear period. The 3x larger flow fails every 2-3 months. And I would like to operate both valves at 50% greater rate, while extending the repair frequency for the problem valve out to once per year.

Feed A Feed B
Vol flow, gph actual 12.0 36.7
Vol flow, gph desired 16.7 51.6
Op temp, C 50 120
Max dp avail pr, psi 325 325
Density lb/gal 12.55 11.35
Visc, cP 14 7

 

[hollerg]

Here is the missing flow curve

 

[unclesyd]

Your OP states poppet valve and the print is labeled injector. We design and and make our own injector quills for polymer service and use Hast C for all wetted parts due to corrosion/erosion problems.

When you saw problems was part A made from 316 or Hast C?

If part A was made from Hast C are your process fluids oxidizing or reducing?

People will stay from Hast C due to machining difficulty.

 

[hollerg]

The problem exists with the larger flow, regardless of material. I do not know whether to consider it oxidizing or reducing. The pH is 3 (carboxylic acid), trace water, trace NaCl, ppm level of HCl, trace phenol. Damage was been far worse with the Hast C & B (lasted 1 wk) than INCONEL 718 (lasts 2-3 mo). This is an injector quill, but isn't the functionality of the spring and area the same as a differential poppet, just configured to have the sealing point at the tip? If not, please point out what other functional differences there are.

 

[hollerg]

So, who makes such check/injector quills?

 

[unclesyd]

Does the above composition represent whats being injected or is it the process stream?

If not what is the composition of the stream being injected?

Your arrangement appears to be setup to insure that the material being injected into the process stream is a higher pressure than the process stream. This is to prevent backflow of the process stream.

 

[hollerg]

The composition is what is being injected through the orifice. The outlet side chamber contains 50% caustic. The materials neutralize each other. There is no general corrosion, only the errosion of the orifice.

The inlet side is kept higher to prevent backflow. The pressure is set ~ 100 psi above the outlet. The feed systems both have pressure oscillation. Feed pumps are simplex diaphragm type w/ pulsation dampener, which is not perfect.

I was told that the primary function of this quill is to prevent backflow. Is this consistant with the design?

When the valve wears, oscillations become greater in amplitude, plugging becomes more likely and instantaneous flow more variable.

 

[unclesyd]

One other thing that might be going on in your arrangement is that the stem, part C, might be suffering from flow induced vibration causing cavitation. This would greatly enhance any erosion problems.

Where are you seeing the erosion?

Normally a valve to accomplish this isn't nearly as complicate as your valve. An injection quill will a small chamber over a spring loaded ball check valve to prevent backflow.
Here are what would be called standard injection quills. There are numerous variations on this arrangement.

http://www.koflo.com/injection.html

http://www.primaryfluid.com/pdf/Injection_Quills.pdf

 

[hollerg]

The stem and orifice are flush with the interior chamber to prevent the unmeltable reaction product from entering the device. The solids strongly agglomerate. They pack the tip tight and plug when they get back into the passage.

Wear seems to be from a glancing blow on the exit edge of the orifice, thining a point on the oulet side of the orifice first. As that point wears, a worn shiny spot develops on the outlet face of the tip (the side facing the cavity). The inside does not show a shiny spot, just the eventual enlarged asymetric oblong opening.

Would the vibration effect result in the tip of the stem being damaged? The stem tip is rarely damaged.