URETHANE INDUSTRY GLOSSARY - O

A seal or gasket that has a round shape (like the letter O) and a round cross section.

See hydroxyl group.

Is the number of milligrams of KOH (potassium hydroxide) that is chemically equivalent to the activity of a specified weight (in grams) of the polyol. This number is used in calculating the equivalent weight of the water and polyol for the purpose of determining stoichiometry or index of a formula .

A mixing device with a special valve section capable of dispensing an accurate amount of well mixed foam ingredients at periodic intervals. Start and stop should be virtually instantaneous with no variation in foam quality from the first drop to the last drop. Time 'on' and 'off" can be controlled by a wide variety of methods ranging from manual movement of a valve lever to automatic timer control of an actuator for the valve section.

A system of paper handling for the lining of conveyors in continuous slab foam processing, based on a single roll of paper that is wide enough to form the bottom plus both sides of the trough. For 84 inch wide conveyors rolls of paper as much as 13 feet wide are required. Not all styles of paper can be purchased in these widths, particularly release papers; and wrinkling problems may occur if tensioning of the roll by the paper mill has been poor or if paper alignment is bad. Because of this many manufacturers use the more complex three roll paper feed system.

A system for the production of urethane foam in which none of the isocyanate portion has been prereacted with any portion of the polyol prior to final mixing. A minimum of 2 components are required, and more than 2 are often used. The ratios between the two major components are normally somewhere between 50/50 and 70/30 for most formulations.

A term applied to foam cell structure characterized by interconnecting cells or bubbles. Flexible foam should be 100% open celled for best quality. This characteristic is difficult to measure directly in flexible foam, and several indirect tests are in use that measure the air flow through a sample of a certain size and thickness.

A term which refers to the practice of pouring into a cavity having a closed bottom and sides but an open top. The mold may be shallow or deep. It is generally not the most economical way to mold a product but may have an Application where minimum internal mold pressures are required.

Are a family of urethane foam catalysts that are noted for their rather specific influence on the gelation reaction. By properly combining an organotin catalyst with an Amine catalyst such as triethylenediamine, a good balance between blowing and gelation reactions can be achieved. The most commonly used catalyst of this type is probably stannous octoate although dibutyltin dilaurate and others of the dibutyltin group are also used.

A term which refers to the practice of determining the density of the uncut foam Block in order to provide data for process analysis. By knowing the density at this point, an accurate gas loss value can be computed, and trim loss can be more easily calculated on a weight basis instead of on a volume basis. Not all foam producers bother with this intermediate step. To avoid guessing, Block height is usually averaged by taking the maximum center height of the crown and subtracting % inch.

The amount of unwanted excess of foam that has been poured into a mold either intentionally or unintentionally. See mold packing, and packing.

A switch actuated by movement of a diaphragm or bourdon tube located near the pump in the flow circuit and arranged to cut off the power to the pump drive motor. This device protects the fluid circuit against damage from over pressurization. Other types of Overpressure protection devices are available such as pressure relief valves and blowout disks. See cut-off switch.

A shortened form of overpressure cut-off switch.

A term in urethane foam spray Applications which refers to the particles of atomized material that hit outside the intended target area. With some equipment, formulations, and environmental conditions this may amount to as much as 50%of the material sprayed; with others it may be as low as 5%. Usually the finer the atomization the smoother is the surface of the foam applied, but the higher is the percent of overspray.

The addition of oxygen to a compound or the reduction of hydrogen.