Imperial Gallons per Minute (imp-gal/min) to Cubic Centimeters per second (cm³/s) conversion

What is the Imperial Gallon per Minute?

The imperial gallon per minute is a unit of volumetric flow rate, measuring how many imperial (UK) gallons of liquid pass a point each minute. It is common in British and Commonwealth plumbing, pumping, and irrigation specifications.

Definition

One imperial gallon per minute equals one imperial gallon (4.54609 litres exactly) of volume flowing every 60 seconds:

$$1\ \text{imp-gal/min} = 0.0757682\ \text{l/s}$$

Because the imperial gallon is defined as exactly 4.54609 L, the exact relation is $4.54609 \div 60 = 0.0757681\overline{6}$ L/s. Note that the imperial gallon is about 20% larger than the US liquid gallon (3.785411784 L), so an imperial gpm is a larger flow than a US gpm.

Origin and History

The imperial gallon dates to the British Weights and Measures Act of 1824, which fixed it as the volume of 10 pounds of distilled water. It was redefined in 1976 (effective 1985) as exactly 4.54609 litres. The "per minute" flow rate arose naturally from waterworks and pump ratings, where minutes are a convenient interval for reading meters and sizing equipment.

Law and Notable Facts

The imperial gallon remains a legal unit in the United Kingdom and several Commonwealth nations, though the litre per second and cubic metre per hour are the SI-based standards for engineering. A tap flowing at 1 imp-gal/min delivers about 4.55 litres every minute; UK water-efficiency guidance often rates fittings in litres per minute, where 1 imp-gal/min corresponds to roughly 4.55 L/min.

Real-World Examples and Conversions

• A typical domestic kitchen tap or shower flows around 2 to 3 imp-gal/min (about 9 to 14 L/min).
• 1 imp-gal/min equals 60 imperial gallons per hour, or approximately 4.546 cubic metres per hour when multiplied out over an hour ($0.0757682 \text{ l/s} \times 3600 = 272.77$ litres/hour, i.e. 0.27277 m³/h).
• To convert to US gallons per minute, multiply by 1.20095: 1 imp-gal/min ≈ 1.201 US gpm.
• A small garden pump rated at 10 imp-gal/min moves about 0.758 litres per second, enough to fill a 200-litre water butt in roughly 4.4 minutes.

What is Cubic Centimeters per second?

Cubic centimeters per second (cc/s or $\text{cm}^3/\text{s}$) is a unit of volumetric flow rate. It describes the volume of a substance that passes through a given area per unit of time. In this case, it represents the volume in cubic centimeters that flows every second. This unit is often used when dealing with small flow rates, as cubic meters per second would be too large to be practical.

Understanding Cubic Centimeters

A cubic centimeter ($cm^3$) is a unit of volume equivalent to a milliliter (mL). Imagine a cube with each side measuring one centimeter. The space contained within that cube is one cubic centimeter.

Defining "Per Second"

The "per second" part of the unit indicates the rate at which the cubic centimeters are flowing. So, 1 cc/s means one cubic centimeter of a substance is passing a specific point every second.

Formula for Volumetric Flow Rate

The volumetric flow rate (Q) can be calculated using the following formula:

$$Q = \frac{V}{t}$$

Where:

• $Q$ = Volumetric flow rate (in $\text{cm}^3/\text{s}$)
• $V$ = Volume (in $\text{cm}^3$)
• $t$ = Time (in seconds)

Relationship to Other Units

Cubic centimeters per second can be converted to other units of flow rate. Here are a few common conversions:

• 1 $\text{cm}^3/\text{s}$ = 0.000001 $\text{m}^3/\text{s}$ (cubic meters per second)
• 1 $\text{cm}^3/\text{s}$ ≈ 0.061 $\text{in}^3/\text{s}$ (cubic inches per second)
• 1 $\text{cm}^3/\text{s}$ = 1 $\text{mL/s}$ (milliliters per second)

Applications in the Real World

While there isn't a specific "law" directly associated with cubic centimeters per second, it's a fundamental unit in fluid mechanics and is used extensively in various fields:

• Medicine: Measuring the flow rate of intravenous (IV) fluids, where precise and relatively small volumes are crucial. For example, administering medication at a rate of 0.5 cc/s.
• Chemistry: Controlling the flow rate of reactants in microfluidic devices and lab experiments. For example, dispensing a reagent at a flow rate of 2 cc/s into a reaction chamber.
• Engineering: Testing the flow rate of fuel injectors in engines. Fuel injector flow rates are critical and are measured in terms of volume per time, such as 15 cc/s.
• 3D Printing: Regulating the extrusion rate of material in some 3D printing processes. The rate at which filament extrudes could be controlled at levels of 1-5 cc/s.
• HVAC Systems: Measuring air flow rates in small ducts or vents.

Relevant Physical Laws and Concepts

The concept of cubic centimeters per second ties into several important physical laws:

• Continuity Equation: This equation states that for incompressible fluids, the mass flow rate is constant throughout a closed system. The continuity equation is expressed as:

  $A_1v_1 = A_2v_2$

  where $A$ is the cross-sectional area and $v$ is the flow velocity.

  Khan Academy's explanation of the Continuity Equation further details the relationship between area, velocity, and flow rate.

• Bernoulli's Principle: This principle relates the pressure, velocity, and height of a fluid in a flowing system. It states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.

  More information on Bernoulli's Principle can be found here.