Conversion from Gallons per second to US Gallons per hour

Information about the Gallon per second (gal/s)

The gallon per second is a unit of volumetric flow rate equal to one imperial gallon passing a point every second. Its symbol is gal/s. The imperial gallon is 4.54609 litres, defined in 1824 as the volume of ten pounds of water at a stated temperature, so one gallon per second moves about four and a half litres — and, conveniently, about ten pounds — every second.

Firefighting is the discipline that works at this scale. A hose reel delivers a fraction of a gallon per second, a standard hose line 1 to 2, and a major pumping appliance 10 or more. British fire service practice quoted pump capacities in gallons per minute for most of the twentieth century, and the per-second figure is what a hydraulic calculation of pressure loss in the hose actually uses.

Large pumps and water mains reach it easily. A borehole pump on a farm might deliver half a gallon per second, a district water main several tens, and a river intake for a power station hundreds. Since the gallon of water weighs ten pounds, a flow in gallons per second converts to a mass flow in stones per second by dividing by 1.4, an arithmetic that older British engineering handbooks used freely.

Flood and drainage engineering in Britain used the unit until metrication. Culvert capacities, pumping station ratings and land drainage schemes were designed in gallons per second or per minute, and much of the surviving infrastructure still carries plates giving its capacity in those terms, which anyone assessing an old asset must convert with care.

The imperial gallon must be distinguished from the American one, which is 3.78541 litres — about twenty per cent smaller. A pump rated 10 gallons per second delivers 45.5 litres per second in Britain and 37.9 in the United States, a difference far too large to ignore in any calculation of capacity or of cost.

For scale, one gallon per second fills a domestic bath in about twenty-five seconds, and 0.22 gallons per second is one litre per second. A flow of ten gallons per second is a small stream, running at about 45 litres per second.

One gallon per second equals about 4.546 litres per second, about 0.004546 cubic metres per second, or about 1.201 US gallons per second.

Information about the US Gallon per hour (gal US/h)

The US gallon per hour is a unit of volumetric flow rate equal to one United States gallon passing a point every hour. Its symbol is gal US/h, commonly abbreviated GPH. At 3.785 litres to the gallon, an hour at this rate delivers a little under four litres, which places it among the slow, continuous flows of heating, irrigation and fuel systems.

Drip irrigation is its most familiar use in America. Emitters are sold rated at 0.5, 1 and 2 gallons per hour, and a garden bed is designed by choosing an emitter for each plant and multiplying by the number of plants. A zone of two hundred one-gallon emitters draws 200 gallons per hour, and a two-hour cycle applies 400 gallons — figures a homeowner can check against the water bill.

Oil burners are rated in it in the United States, exactly as in Britain. A residential oil furnace carries a nozzle marked 0.75 or 1.00 gallons per hour, and multiplying by about 140,000 British thermal units per gallon gives the burner's firing rate. The nozzle is thus both a fuel metering device and the effective rating plate of the appliance.

Water heaters and small appliances follow. A tankless water heater's recovery, an ice machine's water consumption, a humidifier's evaporation rate and a coffee urn's draw are all commonly expressed in gallons per hour, since these appliances run more or less continuously and are chosen to match a daily demand.

Fuel consumption of engines under steady load is quoted this way in American practice. A generator burns 0.5 to 3 gallons per hour depending on size and load, a boat's engine several, and a large marine diesel dozens. Dividing the tank capacity by the hourly rate gives the endurance, which for a boat is the number that actually matters.

For scale, one US gallon per hour is about 3.79 litres per hour, and 264 gallons per hour is about a cubic metre per hour. Sixty gallons per hour is one gallon per minute, so the two American flow units are connected by the same factor that connects the minute to the hour.

One US gallon per hour equals about 3.785 litres per hour, about 0.003785 cubic metres per hour, or about 0.8327 imperial gallons per hour.