Keystones blowing out of a pin

[thebigpeeler]

Hey guys,

Ive always racked my beer into a steel cask and then the rest into bottles, but recently I bought some plastic pins, and for some reason they keep blowing out the keystones which is as you can imagine, annoying as hell!

Im filling them up to the brim before knocking in the shive, and im using rubber keystones.

I ferment out completely, then crash down to 5 degrees for a few days, dump some of the yeast, then bring it back up to 20. I then add priming sugar to the pin/cask.

I was sure (and still am) a pin is half that of a cask, so ive literally just been halving the amount id normally put in a steel cask. Usually id add 220g of dextrose and let it sit at ~20 degrees Celsius, so I halve that and put 110g in a pin. The FG is stable for 48 hours before i crash, i sometimes even rack at crash temperature and let it come up to room temp (~2- degrees) naturally and thats never been a problem, until i stared using plastic pins.

Any ideas guys?

Thanks!

Oli

[thebigpeeler]

Id just like to add that the bottles are fine, no bottle rockets, which i thought may rule out over priming as i add the same amount of sugar per volume to them as i do with the pins.

[thebigpeeler]

But then again i dont know how much pressure a cask/pin is designed to take, im assuming not as much as a keg or bottle

[Mr. Dripping]

I may be wrong on this, but I seem to remember seeing something about the plastic pins having a slightly larger aperture than the metal ones.

[will_raymo2000]

Looking at it, it seems there are various sizes available for the keystone and the shive. It seems to depend on whether it is a metal or plastic cask and also what size aperture it is.

Maybe give one of these manufacturers a ring or alternatively ring the supplier of the pin you bought and ask what is recommended for the pin.

[scuppeteer]

There are a couple of types of keystone, so check which you need.

Also never brim a cask. You need to leave ullage space for the CO2 build up. Casks can only stand so much pressure and will obviously find the weakest point in which to vent. IE the shive or Keystone.

[thebigpeeler]

Do you think its down to overpriming? ive seen suggestions of around 80g and im using 120g ish. Apparently its the correct keystone so it could be the ullage space.

After reading more into priming, im aware of people racking 2pts above FG, which by my math would contribute 1 volume of co2, which seems to be the norm when racking to casks. Im priming enough to give 2.3 volumes of co2, do you think this is the problem?

thanks for the advice so far by the way guys

[thebigpeeler]

I mean, is a pin plus keystone designed to handle pressures of 2.3 volumes of co2? id have thought it would be but after them blowing im not sure. Ive always used steel casks but now ive moved to plastic pins for the time being, and none of the pins have survived!

[Mr. Dripping]

On the priming issue, I've no direct experience of filling pins/casks, but I've done a lot of poly pins for serving through a beer engine. 30g of sugar in 20 litres of beer is ample to provide sufficient carbonation for English style ales IMO.

[thebigpeeler]

Thanks for the advice man, sounds like i realy need to knock back on the priming sugar. I just dont understan how the steel casks have always survived 240g of priming sugar for this long if this is the case

[Mr. Dripping]

I should add, part of the reason I prime low is that I chill my beers (as I see from the OP you also do) very close to zero degrees for at least 5-8 days generally....this helps retain some of the fermentation co2 and the priming need is reduced. Warming the casks up brings the co2 out of solution, which could be a contributory factor. ATB

[fego]

I've had two blow outs using plastic pins, one key stone and one chive. I put them both down to over-priming plus warm temperature. I now prime with just 35g of sugar after full primary fermentation....

btw, on the key stone blow out, I just threw 5 sugar cubes in and put a new key stone in, left it a couple of weeks and it was perfect condition.

[thebigpeeler]

i just realised i made a typo in my original post, i didn't mean to put ~2 degrees i meant ~20 degrees, basically room temperature. After doing a bit of searching around, it seems like im storing the cask too warm. This is my normal schedule:

1. Wait for a stable FG for 48 hours
2. Crash to 5 degrees for 2 days
3. Rack and prime at 5 degrees
4. Let the cask come back up to room temp ~20 degrees

I assumed storing it cool would mean the priming sugar wouldn't be eaten up by the residual yeast and therefore wouldnt carbonate, so i thought id bring it into a good temp for the yeast to eat it up, and clean up some of the by-products of primary fermentation. Am i wrong?

[thebigpeeler]

Whats really bugging me is that I've always had the same schedule, and always stored the casks at the same temp, and ive never had a blowout or a bottle rocket. Im using the same grams of dextrose per litre in the steel cask to prime it, as i am the plastic pins yet I'm having problems.

I've also always filled them up to the brim with no head space, and the apertures for the keystone of both the plastic pin and steel cask are absolutely the same, and I'm also using the correct keystone.

This is driving me nuts! i can see that i must be over priming, but how have i never had a problem with the steel casks?

[paulg]

I posted a question ref priming a pin cask after I blew out a shive.I had added 80 grams sugar to prime .In a reply by critch he said he aims for 1.7 volumes priming but I think it was green paddy that stated you ran the risk of blowing out shives.I have since added 45 grams with no problems and as I use a beer engine i have had no issues with lack of condition in the beer

Interestingly if you use the calculator on brewers friend below

http://www.brewersfriend.com/beer-priming-calculator/

you get for 1.7 volumes with beer temperature at 20 degrees by priming with 101 grams DME
but if you change the beer temp to 5 degrees you only need 22 grams for 1.7 volumes 101 grams gives you 2.3 volumes.
you stated you cold crash the beer ,which I also do but then warm again which I dont I then store at 20 c for a week after racking to cask before I transfer to a fridge at 12 c

just my 2p worth