GPD means Gallons Per Day.
We have the British gallon and the USA gallon. The gallon is a unit of measurement for volume and fluid capacity in both the US customary units and the British imperial systems of measurement. Three significantly different sizes are in current use:
- the imperial gallon, defined as 4.54609 litres, which is used in the United Kingdom, Canada, and some Caribbean nations;
- the US gallon defined as 231 cubic inches (exactly 3.785411784 litres), which is used in the US and some Latin American and Caribbean countries; and
- the US dry gallon, defined as 1⁄8 US bushel (exactly 4.40488377086 litres).
We use the USA gallon which is exactly 3.785411784 litres
When it comes to Reverse Osmosis Machines. It is generally accepted that machines are named according to the output of the RO membrane.
For example, Our 800GPD domestic machine
One day has 24 hours.
800GPD means 800 Gallons x 3.785411784 Litres which should give 3028.33 Liters in 24 hours which means 126.18 litres per hour.
In order to get the correct flow, you will need to need to feed the machine with 10 bars pressure at 15% recovery (1000 lph )
But, our 800G Domestic machine has 2 diaphragm pumps which is not meant to run long hours. You can run it for a maximum of 1 hour each time. Thereafter the pumps will get too hot, and the pump head or diaphragm will burn out.
Also the flow rate is around 90 Litres per hour based on Johannesburg water which has an average TDS of 100.
The purpose of this machine is to be used where more water is required than the domestic RO system. This unit is Tankless. It can be used in restaurants where you will need to fill up water for customers. But it is not meant to be for continuous use, especially when you need to fill up big tanks.
We have had customers who connect the domestic 800 GPD to a 5000 litre tank and the pumps will burn out before filling up the tank. This is not due to a bad quality machine but the incorrect use.
It is very import to know how much water is required for your application for us to to offer you the correct size machine.