Fire Resistant Hydraulic Fluids

Fire resistance is becoming an absolute requirement in hydraulic fluids for more and more users. Each year fire-resistant fluids are being used in more types of applications and in more industries. Most of the usage involves one of the major traditional types of fire-resistant fluids. However, the entire field of hydraulic fluids and the industries served are focusing very sharply on water because it does not burn: it is 100% fire-resistant.

Water brings several important properties to a hydraulic fluid: non-flammable, economic, readily bulk modulus, stable, non-toxic, non polluting, easy to dispose of.

But its use is limited by: high freezing point, corrosiveness, evaporation at high temperatures, poor lubricating properties, low viscosity.

The non-corrosive and non-volatile nature of petroleum products, plus their outstanding lubricating properties, make oil-base hydraulic fluids the most commonly used. With additives, they are even more useful in terms of better performance and wide applicability.

In terms of fire resistance, the ideal fluid should not burn. It should also be inexpensive and present no disposal problems. Low cost and easy disposal are especially important in very large systems.

To combine into one fluid the ideal and the practical, the starting point could be water with modifying additives such as oil and chemicals. The additives would give the water some of the lubricity, load carrying ability, and the corrosion and wear resistance of oil.

Water-additive-type fluids are oil-in-water emulsions - also called soluble oils – or water plus chemical additives. Soluble oil mixtures contain 2-10% oil dispersed in the water; chemicals in water-chemical fluids are at 2-5%.

Chemical-type additives present no disposal problems and generally are simpler to maintain. One type of chemical additives is a highly polar compound that is adsorbed on hydraulic system surface where it forms a film to protect against corrosion and reduce the coefficient of friction. A second type containing a reactant additive with metallic ions in tap water to form a metal soap which serves the same functions as polar compound. Because they are synthetic and biodegradable, chemical additives generally do not form an oil slick on water. These fluids are usually compatible with standard seal, house and piping materials. They are suitable for applications where high viscosity is not essential and where disposal has been a problem.

UNIT 2

Text 1

Слова и словосочетания для запоминания

1. sealing - уплотнение

2. rust - ржавчина

3. prevention - защита, предотвращение

4. oxidation - окисление

5. resistance - сопротивление

6. emulsification - превращение в эмульсию

7. fluidity - текучесть

8. wear - износ

9. contaminants - примеси

10. discharge - разгрузка, сливать

1. Прочтите следующие интернациональные слова и объясните их значение

Design, construction, operation, oxidation, adequate, magnitude, reproduction, separation, application, industrial, compromise, component

2. Переведите на русский язык следующие словосочетания. Объясните чем выражено определение в этих словосочетаниях:

Smooth efficient and economical operation, good system design, fluid properties, efficient transmission of power, system components, lubricant sealing medium, life-resistance, rust prevention, oxidation resistance, power valve

3. Найдите в тексте английские эквиваленты следующих русских слов и

словосочетаний:

обеспечить эффективную передачу энергии, этим требованиям отвечают, вода – единственная жидкость, имеющая определенное применение, для определенных областей применения, ржавление можно предотвратить

4. Проанализируйте следующее предложение с грамматической точки зрения. Переведите:

Smooth, efficient and economical operation of any hydraulic power system depends as much on the liquid which transmits power as on the design construction and operation of the mechanical parts

.

Basic Requirements

Minimum requirements of a hydraulic medium include low compressibility and adequate fluidity to permit efficient transmissions of power. These requirements are met by many liquids.

Primary functions of the hydraulic fluid are transmission of force applied at one point in the system to some other location, and reproduction of any change in direction or magnitude of this force. In addition the fluid must:

1. Provide an adequate seal between moving parts.

2. Protect system components against rusting and corrosion.

3. Minimize wear of moving parts.

4. Permit rapid settling and separation of insoluble contaminants that enter the system.

Water is the only practical fluid for certain applications where great volumes are required. Water is used in open systems which discharge to waste. Typical open systems are those which operate bascule bridges, lock gates and caissons.

However, water has obvious disadvantages:

1. It promotes rusting;

2. Its lubricating powers are negligible;

3. It can be used only in a relatively restricted range of temperatures.

Rusting can be counted by the use of aqueous emulsions of “soluble” oil; but water , in general, remains unsuitable for circulating systems.

Mineral oil is a lubricant, sealing medium and rust preventive in addition to its primary function as the hydraulic medium.

Petroleum oils are ideally suited for the majority of industrial hydraulic applications. They are not applicable, however, where life-resistance is required for hazardous industrial applications. 1520