Pints per second (pnt/s) to Cubic Millimeters per second (mm³/s) conversion

What is pints per second?

Pints per second (pint/s) measures the volume of fluid that passes a point in a given amount of time. It's a unit of volumetric flow rate, commonly used for liquids.

Understanding Pints per Second

Pints per second is a rate, indicating how many pints of a substance flow past a specific point every second. It is typically a more practical unit for measuring smaller flow rates, while larger flow rates might be expressed in gallons per minute or liters per second.

Formation of the Unit

The unit is derived from two base units:

• Pint (pint): A unit of volume. In the US system, there are both liquid and dry pints. Here, we refer to liquid pints.
• Second (s): A unit of time.

Combining these, we get pints per second (pint/s), representing volume per unit time.

Formula and Calculation

Flow rate ($Q$) is generally calculated as:

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

Where:

• $Q$ is the flow rate (in pints per second)
• $V$ is the volume (in pints)
• $t$ is the time (in seconds)

Real-World Examples & Conversions

While "pints per second" might not be the most common unit encountered daily, understanding the concept of volume flow rate is crucial. Here are a few related examples and conversions to provide perspective:

• Dosing Pumps: Small dosing pumps used in chemical processing or water treatment might operate at flow rates measurable in pints per second.
• Small Streams/Waterfalls: The flow rate of a small stream or the outflow of a small waterfall could be estimated in pints per second.

Conversions to other common units:

• 1 pint/s = 0.125 gallons/s
• 1 pint/s = 7.48 gallons/minute
• 1 pint/s = 0.473 liters/s
• 1 pint/s = 473.176 milliliters/s

Related Concepts and Applications

While there isn't a specific "law" tied directly to pints per second, it's essential to understand how flow rate relates to other physical principles:

• Fluid Dynamics: Pints per second is a practical unit within fluid dynamics, helping to describe the motion of liquids.

• Continuity Equation: The principle of mass conservation in fluid dynamics leads to the continuity equation, which states that for an incompressible fluid in a closed system, the mass flow rate is constant. For a fluid with constant density $\rho$, the volumetric flow rate $Q$ is constant. Mathematically, this can be expressed as:

  $A_1v_1 = A_2v_2$

  Where $A$ is the cross-sectional area of the flow and $v$ is the average velocity. This equation means that if you decrease the cross-sectional area, the velocity of the flow must increase to maintain a constant flow rate in $m^3/s$ or $pint/s$.

• Hagen-Poiseuille Equation: This equation describes the pressure drop of an incompressible and Newtonian fluid in laminar flow through a long cylindrical pipe. Flow rate is directly proportional to the pressure difference and inversely proportional to the fluid's viscosity and the length of the pipe.

  $Q = \frac{\pi r^4 \Delta P}{8 \eta L}$

  Where:

  • $Q$ is the volumetric flow rate (e.g., in $m^3/s$).
  • $r$ is the radius of the pipe.
  • $\Delta P$ is the pressure difference between the ends of the pipe.
  • $\eta$ is the dynamic viscosity of the fluid.
  • $L$ is the length of the pipe.

What is Cubic Millimeters per Second?

Cubic millimeters per second ($mm^3/s$) is a unit of volumetric flow rate, indicating the volume of a substance passing through a specific area each second. It's a measure of how much volume flows within a given time frame. This unit is particularly useful when dealing with very small flow rates.

Formation of Cubic Millimeters per Second

The unit $mm^3/s$ is derived from the base units of volume (cubic millimeters) and time (seconds).

• Cubic Millimeter ($mm^3$): A cubic millimeter is a unit of volume, representing a cube with sides that are each one millimeter in length.

• Second (s): The second is the base unit of time in the International System of Units (SI).

Combining these, $mm^3/s$ expresses the volume in cubic millimeters that flows or passes through a point in one second.

Flow Rate Formula

The flow rate ($Q$) can be defined mathematically as:

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

Where:

• $Q$ is the flow rate ($mm^3/s$).
• $V$ is the volume ($mm^3$).
• $t$ is the time (s).

This formula indicates that the flow rate is the volume of fluid passing through a cross-sectional area per unit time.

Applications and Examples

While $mm^3/s$ might seem like a very small unit, it's applicable in several fields:

• Medical Devices: Infusion pumps deliver medication at precisely controlled, often very slow, flow rates. For example, a pump might deliver insulin at a rate of 5 $mm^3/s$.

• Microfluidics: In microfluidic devices, used for lab-on-a-chip applications, reagents flow at very low rates. Reactions can be studied using flow rates of 1 $mm^3/s$.

• 3D Printing: Some high resolution 3D printers using resin operate by very slowly dispensing material. The printer can be said to be pushing out material at 2 $mm^3/s$.

Relevance to Fluid Dynamics

Cubic millimeters per second relates directly to fluid dynamics, particularly in scenarios involving low Reynolds numbers, where flow is laminar and highly controlled. This is essential in applications requiring precision and minimal turbulence. You can learn more about fluid dynamics at Khan Academy's Fluid Mechanics Section.