Determining yarn fiber involves both physical examination and burn tests. First, inspect the yarn for characteristics like sheen, which indicates silk or synthetic fibers, or a halo, suggesting wool. Next, the burn test helps identify the fiber type based on smell, flame, and residue. Burn a small sample in a safe, non-flammable area. Wool and silk emit a burning hair smell and leave a crushable residue, indicating protein-based fibers. Cotton and linen, being plant-based, will smell like burning paper and leave fine ash. Synthetics like polyester melt and harden upon cooling, emitting a chemical smell. Always conduct this test with caution and in a well-ventilated space to avoid inhaling fumes.

The maximum psi (pounds per square inch) rating for 200 class PVC pipe refers to the maximum pressure it can safely handle. Typically, for PVC pipes, this is determined by the pipe's Schedule number or SDR (Standard Dimension Ratio). For a 200 class PVC pipe, this often means a maximum pressure rating around 200 psi, though it's crucial to check the manufacturer's specifications for the exact rating. Pipes with a 200 psi capacity are commonly used in irrigation, water distribution, and light-duty industrial applications. It's important to select a pipe that meets both the pressure and the material suitability for the intended use to ensure safety and longevity of your project.

Suspensions, colloids, and emulsions are all mixtures of two or more substances, but they differ in particle size and behavior. Suspensions are heterogeneous mixtures where the particles are large enough to settle out over time, like sand in water. Colloids are mixtures where the particles are smaller and don’t settle out, allowing them to be evenly distributed throughout the mixture; milk and fog are examples. Emulsions are a type of colloid specifically involving the mixing of liquids that usually don't mix, like oil and water; emulsifying agents are often necessary to keep the mixture stable. Each of these mixtures plays crucial roles in various industries, from food and beverages to pharmaceuticals, by tailoring the mixture's properties to specific applications.