![]() Other system components are less sensitive to viscosity. The pump and hydraulic motor are most sensitive to viscosity, so you must be sure to only use suitable oil according to the manufacturer specifications. ISO grades are used most commonly with hydraulic oils. Fluids are most commonly measured in Sabolt Universal Seconds (SUS) or Sabolt Seconds Universal (SSU), which is measured with a Saybolt Viscosimeter. As an example: 30W oil flows much faster at higher temperatures. If the tested oil takes more than 1,000 sec for the 65 ml to flow, the tested oil temperature is increased. Lower viscosity fluids will flow more easily and faster, while high viscosity fluids will flow more slowly. The time measured in seconds for a volume of 65 ml to flow through the orifice is the rating of the oil. The tested oil is brought to 100° F and poured through a standard orifice of 0.0695 in. The most common unit in the United States is the Sabolt Universal Seconds (SUS) or Sabolt Seconds Universal (SSU), which is measured with a Saybolt Viscosimeter. Viscosity- Because an oil’s viscosity changes with temperature, it is always expressed at a reference temperature, usually 100° and 210° F. The viscosity index number indicates the extent of thickness, or resistance to flow, with temperature changes. Viscosity rating is a measure of the oil’s resistance to flow or thickness, and is the single most important characteristic of hydraulic oil. Viscosity index should not be confused with viscosity it is an altogether different kind of rating. ![]() ![]() One of these other chemicals is a viscosity index improver. For these uses, petroleum oil is highly refined to remove undesirable chemicals while other chemicals, such as additives, are added to improve the oil’s performance. Petroleum-based hydraulic fluid has a variety of desirable characteristics, including lubricating and anti-wear properties, so it is often the preferred fluid for hydraulic systems. DMAR Technical Training and DMAR Business Centers USA Photo: Meg Schneider.This technical brief was supplied by Hydramotion. This is the ratio of the time of fl ow of 200 ml of fl uid to the time of fl ow of 200 ml of water at the same temperature in a standardized Engler viscosity meter.viscosities, SSF (Saybolt Seconds Furol) is used. This is the time for 60 ml of fluid to flow through the calibrated orifice of a Saybolt Universal viscometer at a specifi ed temperature, as prescribed by test method ASTM D 88. It is most usually encountered as the centistokes (cSt) (= 0.01 stokes). One stokes is equal to the viscosity in poise divided by the density of the fluid in g cm–3. This is the cgs unit, equivalent to square centimetre per second. One poiseuille is 10 poise or 1000 cP, while 1 cP = 1 mPa It is sometimes referred to as the “poiseuille” (symbol Pl). This is the SI unit of viscosity, equivalent to newton-second per square metre (N Many everyday fluids have viscosities between 0. It is the viscosity of a fluid in which a tangential force of 1 dyne per square centimetre maintains a difference in velocity of 1 centimetre per second between two parallel planes 1 centimetre apart.Įven in relation to high-viscosity fluids, this unit is most usually encountered as the centipoise (cP), which is 0.01 poise. Named after the French physician Jean Louis Marie Poiseuille (1799-1869), this is the cgs unit of viscosity, equivalent to dyne-second per square centimetre.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |