Insect products blocks vent pipe

[CostasV]

Good day to everyone

Recently, we find out that four vent pipes (internal diameter about 8 mm) were blocked by insect products which looked like cocoon. The blockage was from 10 to 40 cm long inside the pipe. The pipes were used to release (generally small quantities) gas from a pressure of about 6 bar, triggering a sequence of movements. And of course, since there was no release of gas no sequence happened. We had to dimantle the vent pipes and clean them using a wire

We have not found any insects, only its products. Normally these pipes are used (flow is passing) twice a year or in an emergency.

Does anyone know how can we protect these pipes from similar blocking in the fuure? I am not sure if putting a "net" at the outlet is a good solution.

Thank you in advance!

Costas

 

[zdas04]

The only way I've found is to schedule blowing the lines out monthly during periods where insects are a problem. When I've put screens over these vents, the bug spit collects on the screen wires and plugs the line faster.

Just plan on blasting gas through them regularly (sometimes you can use canned air with a thin tube and insert the tube past the blockage to blow the stuff out).

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"

 

[kcj]

Looks like white fine cotton? Some sort of nest from very tiny spiders.

I don't have a prevention idea for you, but I have contacts who swear its the most common reason outdoor barbecue grilles are thrown out: over winter, the spiders built nests in the air mixing tubes and the owner thinks the burner is plugged up. Solution in our climate is to clean out with a wire every spring.

Possibly a very large area fine screen tube, within a larger outer tube for weather protection? Or, as previous post suggested, human labor intensive periodic inspection and cleaning.
k

 

[iainuts]

We've had a lot of problems with a type of bee called a Mud Dauber, mostly in Florida. They love to build homes inside small bore tube such as you describe. The nests are very solid, almost like concrete, made from dried mud. They make great plugs if you need to shut off a tube!

The solution is to simply put a vent screen (or "vent protector") at the end of any open tubes. They are like pipe plugs with a piece of screen over the end so the buggers can't get in. You can purchase these from Swagelok, Parker, Allen Aircraft, and other tube fitting manufacturers.

 

[friartuck]

We use large screened outlets on our water tanks in the UK. These are large dia. and due to the size, have a large free area but can stop insects. We call them Bye-law 30 kits (though the bye-laws changed a while ago)

Any decent plumbing supplier should have one.

Friar Tuck of Sherwood

 

[CRG]

Have you considered a flapper cap? Vent screens small enough to keep insects out can be easilly fouled.

 

[CostasV]

Thank you all for your immediate answers

I summarise the solutions
a. periodically blowing the line
b. large area fine screen
c. manufactured vent protector
d. flapper cap

If I understand correctly a flapper cap is a plastic cap that firmly closes the pipe outlet. In case of pressure increase in the pipe, the flapper cap will be blown away (so we should put a wire to use it again if we want).

I think the flapper cap is the solution to my problem!

Thank you all again!

Costas

 

[aspearin1]

A flapper cap can be hinged and spring loaded, (or even just hinged and rather heavy, requiring pressure to lift it, but closes automatically once the pressure is released...Like the old Steam Engine Trains.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[friartuck]

Do the vent pipes ever let air in for any reason??? If so, you may well get a vacuum and suck the tank in??

An anti-vac valve would solve the problem.

Friar Tuck of Sherwood