BEER EQUIPMENT

DRAFT BEER DISPENSING

BEER MUST BE CONSIDERED AS A FOOD PRODUCT AND SHOULD BE TREATED AS SUCH IN THE WAY IT IS HANDLED.  A CARBONATED MALT BEVERAGE BREWED AND AGED TO OBTAIN A PEAK OF PERFECTION MUST BE SERVED AT THE RIGHT TEMPERATURE AND THE CORRECT CO2 CONTENT IN ORDER TO GIVE IT THE CORRECT FLAVOUR AND TASTE SATISFACTION.

DRAFT BEER IS THE SAME AS BOTTLED BEER EXCEPT THAT IT IS NOT PASTEURIZED AND HAS LESS CARBONATION.

DIFFERENT FACTORS MUST BE CONSIDERED TO OBTAIN OPTIMUM BEER RESULTS:

A. TEMPERATURE:

The serving temperature of beer should be around 40F in the glass.  It can range between 38F and 42F without affecting the quality of taste.  Allowances must be made for the warmer glass and the warmth of the hand holding the glass during dispensing.  Draft beer must be stored at 38F to ensure good quality: If allowed to warm up, draft will spoil rapidly since it is not pasteurized.

 

B. PRESENTATION:

The consumer package for draft beer is the glass.   It may vary in size and shape but it must be 'Beer Clean'.  (see Cleanliness)   A correctly drawn draft will appear clear with 3/16" to 1/4" of foam.   As it is consumed, the foam should 'lace' within the glass.

 

C. CLEANLINESS:

(a) Serving Glasses: Serving glasses must be 'Beer Clean'.  A 'Beer Clean' glass will not affect the contents; therefore, the glass cannot have any film or residue from the cleansing agent that will react with the beverage.

(b) Dispensing Equipment: The serving station and storage cooler must be clean and odor free.  Refrigeration condenser coils must be clean to ensure correct temperature, and draft transmission lines must be cleaned and sanitized regularly.  CO2 gas used as propellant must be pure.

 

D. DISPENSING SYSTEM:

The principle of a draft beer dispensing system is to rapidly fill glasses without sacrificing quality.  The faucet delivery should be 2.1 to 2.6 oz per second.  Delivery speed is determined by propellant pressure and line restriction.  In order to deliver a solid, 'handleable' quality product, the system must be balanced within 2 lbs. and gently lifted from the barrel or keg to the faucet.

USE OF CO2 AS A DRAFT BEER PROPELLANT

CO2: CO2 IS PURE AND WILL NOT CAUSE PRODUCT SPOILAGE.  IT CAN HOWEVER CAUSE THE CARBONATION CONTENT OF DRAFT TO INCREASE TO A LEVEL WHICH WOULD MAKE IT IMPOSSIBLE TO POUR DUE TO FOAMING.

 

N2: NITROGEN OR NITROGEN BLENDS ARE FAR SUPERIOR THAN AIR OR AIR CO2 BLEND.  THE NITROGEN WILL NOT AFFECT TASTE AND CAN BE USED WHERE HIGHER PRESSURE IS REQUIRED.

 

AIR: NOT SANITARY - WILL OXIDIZE BEER.  WILL AFFECT TASTE AND QUALITY.

USE THE FOLLOWING EXAMPLE:

A barrel of draft in cooler storage with 10.8 PSI equilibrium pressure and a cooler temperature of 37F produces a product CO2 gas volume content of 2.5 volumes.  This same barrel is placed in service.

When tapped, additional CO2 pressure (say four pounds) is applied (propellant pressure) in order to maintain equilibrium pressure to the dispensing faucet.

As a barrel stands with propellant pressure applied, the product will absorb CO2, increasing the carbonation content.

When enough product is removed to expose the surface of the barrel diameter, at standard absorption rate, the carbonation content will rise from 2.5 to 3.0 volumes in approximately 50 hours.  At this point it will be impossible to draw product at the faucet without excessive foam.

The propellant pressure can be increased to overcome foam temporarily but if the barrel contents are not used within a reasonable time, the carbonation content will continue to rise resulting in unservable product due to foaming and excessive carbonation content.

On a 100' run, the propellant pressure would be minimum of 8 PSI above the equilibrium pressure.  The serving time on this barrel would be less than 10 hours.  Should there be several barrels jumpered, then the problem is slowed as only the barrel contents directly exposed to CO2 will absorb rapidly.

IN CONCLUSION: For long runs, nitrogen or air must be used as a propellant to reduce foam problems.  If just compressed air is used, then CO2 leaves the product, oxidation occurs and flat unservable product results at the end of the keg contents.

Our recommendation would be to use CO2 where possible, to use nitrogen or CO2/N2 blend when propellant pressures exceed 4 PSI or to use as a last resort an air compressor/CO2 injector unit on all runs that require more than 4 PSI propellant pressure.  This unit, also called a stabilizer pump is an air compressor that automatically blends CO2 with the compressed air so that product can always be delivered with the correct carbonation content regardless of the run length.

PRESSURES AFFECTING DRAFT BEER

EQUILIBRIUM PRESSURE (E.P.):

This is the static pressure in the barrel or keg filled with the product containing the correct carbonation content.  This pressure varies directly proportionately with temperature.

 

LESS THAN EQUILIBRIUM PRESSURE:

Attempting to dispense draft at less than equilibrium pressure is probably the greatest cause of foaming and spitting, resulting in a flat, unservable product.  What happens in this case is CO2 gas is leaving the product in the line before reaching the faucet.

OVER EQUILIBRIUM PRESSURE:

Pressure exceeding equilibrium over a period of time will increase the carbonation content of the product.  A keg in a 38F ambient temperature, with an applied operating pressure of 14 PSI, and an equilibrium pressure of 11.3 PSI (2.50 volumes), will absorb CO2, increasing the carbonation content at a rate of .001 volumes per hour.  Using this same example with an operating pressure of 21 PSI, the carbonation content will increase .022 volumes per hour.  Therefore, at the end of 8 hours:

 

E.P. 11.3 + O.P. 14 = Carbonation Change 2.50 + (.001 x 8)

                                       = 2.508

                                          = New E.P. 11.4

 

E.P. 11.3 + O.P. 21 = Carbonation Change 2.50 = (.022 x 8)

                                        = 2.676

                                            = New E.P. 13.1

 

OPERATING PRESSURE (O.P.)

This pressure is required by a particular dispensing installation made up of the following:  Equilibrium Pressure + Vertical Rise Pressure + Equipment Pressure

 

VERTICAL RISE PRESSURE (V.R.P.)

One pound of static resistance pressure is required for every two feet of vertical rise regardless of transmission line size. (0.42 lbs. per inch)

 

EQUIPMENT PRESSURE (BOOST PRESSURE, B.P.)

This pressure is required to overcome dispensing system pressure drop.  Each keg in the system requires 1/2 lb.

 

Excessive transmission line - see chart, DRAFT BEER TRANSMISSION LINE RESISTANCE AND FLUID CONVERSION.

EXAMPLE INSTALLATION

USING A DIRECT DRAW CABINET:

1. Vertical Rise (21") from top of keg of faucet V.R.P. = 0.9 lbs.

2. One Keg                                                             B.P. = 0.5 lbs.

3. Equilibrium Pressure (2.5 volumes, 38F)       E.P. = 11.3 lbs.

4. Operating Pressure                                          O.P. = 12.7 lbs.

Restriction line (Faucet Choke) is:  60" of 3/16" ID

(57" of tubing + faucet shank) i.e.: 5' x 2.2 = 11 P.S.I.

Dispensing Valve Pour Pressure is therefore, .3 lbs., delivering 2.133 oz. per second.  The system is balanced to less than 2 P.S.I.   Using the above example as a base, let's move the faucet 40' away.

BALANCING THE FAUCET:

1. 3/8" transmission line 40' (40 x 0.064 lbs./ft. = resistance) 2.56 lbs.

2. Remove from the restrictor 1.16' of tubing (2.56 ./. 2.2)

NOTE:  Using 1/4" Poly tubing, 18.33' must be used to equal the 60" length of 3/16" choke.

ALTITUDE: Add 1 lb. for each 2000' above sea level to installation to compensate for lower atmospheric pressure.