Design help-valve type?

[Rod427]

I'm looking for some help with a product I'm designing.
It's a marking device that has a valve at the tip. It is filled with alcohol based liquid and when the tip (see green below) is pressed the liquid flows.
Pretty much I'm reverse engineering a whiteout pen. I want to learn more about this type of valve but I'm not 100% sure what its called. I guess its a check valve but is there a specific term I should be researching. I want to learn more about the sealing area and how they should match up to make a good seal.

Another issue I have is the size of these components. The smallest size is .02" dia and that is .250" long and the female part needs special tooling to machine this profile. I'm thinking about increasing the size but again not 100% confident in my knowledge of this type of valve.

Please let me know any suggestions or need anything clarified

 

[Gholam Baghery]

You can make a small groove in the pen body for an O-ring washer. it is pretty simple and it seals the Alcohol perfectly. Otherwise, you should make a cone with 4 degrees for the pen tip and the body. in this case, you have perfect sealing as well.

 

[hydtools]

Manual override check valve?

Ted

 

[LittleInch]

Spring loaded ball check valve?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[btrueblood]

Spring loaded poppet check valve. The poppet is going to jam over time and usage, due to side loads...or it will leak for the same reason, the poppet will dent or wear the seat into an oval. You might be able to limit the sideways movement if the long prong on the poppet (spring guide) is changed to a sleeve (spring fitting inside the sleeve) so that the o.d. of the sleeve rides in at least 3 points against a tight clearance to the body wall. Does the alcohol carry a pigment or other substance that will leave a "bathtub ring" when the alcohol evaporates? This may clog the pen over time and usage as well, and is a tougher problem to solve. Making the pen dis-assemble-able for cleaning might work. The end of the pen barrel being blunt may lead to wicking of the paint/dye/flux/whatever "around the corner" of the end of the pen and onto the user's fingers. Might be better to have a sharp corner there, and/or grooves on the pen nib to wick the fluid down towards the point.

 

[MacGyverS2000]

Ball point pens are amazingly difficult to get right.

But it should be noted they use a rolling ball at the end rather than a fixed point.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[hydtools]

Dispensing check valve.

Ted

 

[1503-44]

C19 Disspensor valve.

 

[Rod427]

Hi all thanks for the advice thus far.
A couple things to address this is 1 time use and will be filled with < 1ml of dyed liquid. Adding a gasket would help however (from my limited experience) they are expensive for the size and to assemble.
A ball bearing does not work in our application

The Spring loaded poppet check valve is very close to what looking for THANK You!

 

[Gholam Baghery]

Hi Rod 427
As this is one-time use, you can use clear silicone for sealant instead of a washer. It would be very reliable and very cheap. It would be enough to create a groove and fill it with silicon. Take a look at this pic.

After a while, the silicon gets solid and seals the gap perfectly.

 

[btrueblood]

Sigh. Don't use silicone, whatever you do. It's not intended to form a dyanamically loaded seal, would tend to fall apart and crumble after being exposed to alcohol, and is permeable to alcohol in any case. Don't use a "gasket", use an o-ring if you need to seal the device. EPDM would work.

 

[Rod427]

When I say 1 time use I mean, the product will be a single use product but we will be running production, 5-10k/yr.

I also meant o-ring in reference to gasket.

 

[TheTick]

Not really a check valve, as check valves are flow-operated. More like a spool valve.

I wouldn't get hung up on names. Just make sure your seat geometry is good. I've had good results with a sphere seating in a cone. Need good surface quality in both form and finish.

As Gholam Baghery stated, you can use an O-ring for a gasket.