Measuring quantity
Though not really a test as it is the first check of milk collected. Quantity can be measured in volume or weight.
Volume Versus Weight:
As most payment systems are based on milk solid contents, it is more appropriate to measure the weight of milk (1 litre of milk on average weighs 1.031 kg). If you have no other way of determining the weight of the milk and you have determined the specific gravity, you can convert volume into kilos:
litres x specific gravity = kilos.
Container method (volume)
This method uses small containers made either to hold definite quantities of milk such as 1/2 litre, 1 litre or with internal graduations, from which the milk level in the container can be read.
Dipstick method (volume):
If you do not have other measuring instruments, you can use the dipstick method to measure the volume in e.g. a standard 40-litre milk can. The dipstick method uses a graduated stick that can only be used in containers of equal size.
“To make a dipstick, put a stick or rod in the standard can and pour repeatedly exactly half a litre of water in the can, mark the dipstick at the water level with a knife or waterproof marker each time until the can is full. Write the numbers at each mark (e.g. 0.5, 1, 1.5 etc) and your dipstick is ready! Make sure you always use the same can each time you use your dipstick, because the same stick cannot be used for measuring the contents of other types of containers; also make sure it is kept clean!”
Spring balance or electronic scale method (weight):
A spring balance measures the weight of the milk. Please note that this method can easily give wrong readings, and frequent adjustments even on the same day may be necessary. A standard weight has to be used to check and calibrate the reading regularly.
A better method to weigh the milk would be to use a good quality bench weighing scale, or a platform weighing scale. Either the balance or scales should be capable of an accuracy of 0.05 kg and may be the mechanical or the digital type.
Flow-meter method (for larger volumes):
In modern road tankers, the milk is measured by a flow meter, which is a volumetric measurement. A de-aerator is necessary to remove air from the milk; air that may have entered the milk during pumping will result in increased milk volumes.