holder at an appropriate rate to help maintain load temperature in use examples a and b below are examples of how the approximate amount of carbon dioxide snow required for use in a particular application of the method of the invention can be calculated this enables the desired dimensions of a holder according to the invention for the particular application to be determined d 0 085 m equ4 heat in flow through walls and roof equ5 surface area of floor a 2 3 6 m 2 heat in flow through floor equ6 q 2 0 because the container doors remained closed during the trip however tests revealed a relatively high value for co 2 gas loss because of inadequate door seals of 11 kg h m t 43 u00b0 c equ7 total net heat in flow equ8 snow refrigeration capacity r 640 kj h equ9 it should have a high permeable surface to volume ratio of 16 to 4 in order to compensate for high rates of heat in flow through the floor and because of leaking doors a permeable bag similar to the bag 60 but having dimensions 2 m u00d7 1 2 m u00d7 0 15 m covered most of the container roof area and was found to satisfy the above requirements tests showed that woven polypropylene material single end warp twill weave 30 u00d7 16 constitution meet the requirements of d 0 05 m equ10 heat in flow through walls equ11 an average of four deliveries per hour i e n 4 were to be made to deliver chilled.