I own a couple of espresso cafes in my city and business is good and
turnover is brisk.

We have always used a great amount of whipped cream - on drinks and
served with deserts. I started out using the conventional disposable
cannisters of whipped cream, and found them expensive on a per serving
basis.

So, always on he lookout for cost-cutting measures, opted to buy a set
of iSi cream dispensers - a very good investment ... as they produce a
thicker higher quality cream product, and also allow for addition of
flavouring to my base cream mix ... very nice!

The downside of these cream dispensers, is that I seem to go through a
high volume of N20 (notrous oxide) bullets/charges./cartridges ...
which are used to add a pressure base to the dispenser, turning liquid
cream (which is added to the dispenser) into a 'whipped' final form
(which comes out of the dispenser's nozzle).

However, while a cheaper option than the disposable whipped cream
cannisters, the number of N20 bullets/charges./cartridges that I go
through is alarmingly high.

And that is where I decided to look for a bigger and cheaper N20 supply
alternative.

I visited an industrial gas operation that imports tanks of N20 used
for the midical market - 5 feet high, and can store some 26 kg of N20
product - quite the volume alternative compared to a single N20
bullet/charge/cartridge that holds a mere 8 grammes of N20 product.

I need no license or permit to buy the product, and the cost per tank
comes in at USD$175, and a rental of USD$25/month for the 5 foot
clylinder - i.e. I am buying the N20 but not the cylinder, I have to
rent it. Still seems a fair deal ... especially since one single N20
bullet/charge/cartridge will cost me close to USD$1 including freight,
etc...

Doing some arithmetic .... from 1 large cylinder @ 26kg (26,000
grammes) I should be able to get 3,250 small N20
bullet/charge/cartridge servings of gas (26,000 / 8 grammes) .... quite
the saving on a dollar to dollar basis. And even allowing for some
additional wasteage from using the larger cylinder, loss of
pressurisation, etc.... the economies of scale are still very prevalent
in my mind.

So ... how to get the N20 from the large cylinder into the cream
dispenser?

Well, took one of my dispensers to their factory and they can supply me
with a regulator and the hosing/pipes needed to connect the big N20
cylinder to my dispenser ... simply turn the 'tap' on the cylinder and
the N20 should flow directly into the cannister.

Now this is where it gets a little grey ...

How do I gauge how much N20 to put into my dispenser?

Well, my dispenser has a volume of 1litre, and I add two small N20
bullets/charges/cartridges for a 'full load' of liquid cream base ...
so I need 16 grammes of N20.

While I can't possible measure how much N20 I am exactly filling into
every individual cream dispenser, surely there must be a pressure
release mechanism in the dispenser that releases some N20 gas when the
pressure in the dispenser goes above the optimum limit?

I am hoping so.

I already emailed the manufacturer of my dispensers (iSi) asking about
the pressure release function - NOT stating that I intend to use a
large cylinder to re-charge my dispensers ... and will post their reply
along with my test results once I get my large cylinder and hose
mechanism sorted out.

I just thought I might invite some comments about my idea and perhaps
shed a little light on other potential (more economical) gas-refilling
options out there.

Thanks for your time everyone! :-)

Regards,

PaullyP