Ugniai atsparios hidraulinės alyvos

Hidraulinės nedegios alyvos                                                               

Rūšis

Klampumas prie 40ºC, mm2 /s

Tankis, prie 15ºC, kg/m3

Pliūpsnio temperatūra PMCC, ºC

Stingimo temperatūra ºC,

Panaudojimas, savybės

 

 

Molyduval 

Herkules GWW 46 HFC

 

 

 

46

 

 

 

1070

 

 

 

netaikoma

 

 

 

-42

 

Ugniai atspari, vandeningų poliglikolių tirpalo pagrindo saugi hidraulinė alyva

įrangai dirbančiai šalia liepsnos ar kaitros šaltinių, galinčių sukelti gaisrą. Atitinka Europos Sąjungos „7th Report“.

 

 

 

Repsol 

Telex HFC

 

 

 

46

 

 

 

1080

 

 

 

netaikoma

 

 

 

-48

 

HFC kategorijos ugniai atsparus, vandens ir sintetinio glikolio pagrindo hidraulinis skystis.

 Atitinka Europos Sąjungos Liuksemburgo „7th Report“ protokolą.  ISO 6743/4 – HFC; ISO 12922 – HFC.

 

 

Molyduval

Herkules EO 32 HFD

Herkules EO 46 HFD

Herkules EO 68 HFD

 

 

 

35

 

46

 

65

 

 

920

 

920

 

920

 

 

>290

 

> 290

 

300

 

 

-26

 

-21

 

-21

 

HFDU kategorijos sintetinių Poliolio Esterių pagrindo ugniai atspari hidraulinė alyva. Be chloro, nitritų, fosfatų.

 

Nyco

Hydraunycoil FH 4541

 

Hydraunycoil FH 4551

 

 

 

 

48,7

 

 

74,4

 

 

923

 

 

923

 

 

320

 

 

312

 

 

-36

 

 

-30

 

 

Ypač aukštos kokybės HFDU kategorijos hidraulinė alyva

sintetinių POE pagrindu.

Tai pat saugi aplinkai ir bio iri.

 

 

Repsol

Telex Vulcano

 

 

 

68

 

 

 

 

326

 

 

 

-18

 

 

Ypač aukštos darbinės temperatūros ugniai atspari hidraulinė alyva sintetinių esterių pagrindu.

ISO 6743/4 – HFDU; 7th Luxembourg Protocol.

 

Ugniai atsparios alyvos pasirinkimas

Rules for choosing a fire-resistant hydraulic fluid

The overwhelming majority of hydraulic components and systems are designed to use oil-based hydraulic fluids. No wonder; these fluids rarely present significant operating, safety, or maintenance problems. Unfortunately, there are circumstances where using oil-based fluid should be avoided. One common fluid power application is in an environment with potential ignition sources &emdash; an open flame, sparks, or hot metal. In these environments, a leak spraying from a high-pressure hydraulic system could cause a serious fire and result in major property damage, personnel injury, or even death.

Even though most oil-based hydraulic fluids have relatively high flash/fire points (>300° F), small leaks in a high-pressure system can produce a finely atomized spray that can travel significant distances. If an ignition source is encountered, complete ignition of the spray envelope can occur. The alternative is to use a hydraulic fluid that eliminates or significantly reduces this hazard: any of several fire-resistant hydraulic fluids (FRHFs).

The decision to purchase a higher-priced FRHF is perhaps analogous to our income tax dilemma this month; you don't want to pay it, but the alternative is worse. However, there is more to know about FRHFs than just price; there are significant chemical and performance differences that must be understood before specifying a FRHF for any given application. To address this need, this article will briefly review the evolution of FRHFs, the types of fluids that are commercially available, and the advantages and disadvantages associated with each.

How far we've come

The history of FRHF is relatively simple and has been one of slow evolution. As the name implies, the original fluid medium in hydraulic applications was water, and it offered the highest degree of fire resistance possible. However, an acceleration in the performance potential of fluid power systems dictated a need for much better lubricating requirements that could be satisfied only by oil-based fluids.

Apart from isolated segments of basic research, little progress was made in developing suitable FRHFs until the end of World War II. During the war, tragic incidents related to hydraulic fluid fires and major property losses at steel mills and foundries graphically illustrated the urgent need for something to be done. Similar incidents in captive environments such as coal mines during the rapid post-war industrial expansion helped motivate a major joint research effort between government and industry. This work was directed at developing fluids that could replace oil-based hydraulic fluids at a reasonable cost and with no significant reduction in hydraulic system performance. Two basic approaches were undertaken. One involved the introduction of water into the fluid to act as a "snuffer" if the fluid ignited. The other involved synthetic, non-aqueous products whose chemistry resisted burning or generated products of combustion that helped extinguish any flame.

Commercial products in both categories evolved during the 1950s and '60s and are still in use today. In the early 1970s, an additional synthetic type of fluid was introduced to address many of the drawbacks inherent in the earlier types. Since the introduction of each type, many improvements have been made in fire resistance, anti-wear properties, and overall quality.

Where we are

Water glycol and invert emulsion constitute the major fluid types of water-containing products. Water glycol is a true solution of a glycol (such as ethylene glycol) in water, along with a variety of additives to impart viscosity, corrosion protection, and anti-wear properties. A shear-stable thickener, which has improved over the years, represents the novel technology aspect of the fluid. Water glycol contains approximately 40% water. Despite a number of drawbacks, water glycol is the dominant FRHF on the market today and is used in a wide variety of applications.

An invert emulsion also contains approximately 40% water but is a stable emulsion of water dispersed in oil. The outer phase, oil, represents the wetting surface; the inner phase, water, provides the fire retardant-element. Oil-soluble additives provide anti-wear properties, corrosion protection, and emulsion stability. Inverts, at one time, were commonly used but are losing favor in industry today.

Synthetic fluids initially were represented by a class of chemical compounds known as phosphate esters, which are reaction products between phosphoric acid and aromatic ring-structure alcohols. These fluids are extremely fire resistant and have widespread industrial use, as well as military and aircraft service. However, their popularity has declined because of environmental, cost, and compatibility factors.

The other type of synthetic fluids in use are synthetic hydrocarbons, more specifically, polyol esters. These fluids are the reaction products between long-chain fatty acids (derived from animal and vegetable fats) and synthesized organic alcohols. These products contain additives to impart anti-wear properties, corrosion protection, and viscosity modification. Fire resistance results from a combination of high thermal properties and physical characteristics. This is the most recent category of FRHFs and has gained widespread and growing use.

By Robert Gere and Thomas Hazelton

Fire-resistant fluids applications

When the possibility exists that a hydraulic fluid may come in contact with a source of ignition or the surface of very hot equipment, fire-resistant fluids may be used. This potential fire risk exists in applications such as die-casting operations, and continuous casting hydraulics in steel mills or presses that are operated near presses or ovens.

Electro Hydraulic Controls (EHC)

used for governing steam supply to turbine generators are also applications in which high pressures and temperatures dictate the use of fire-resistant fluids to mitigate the potential for dangerous and expensive fires.

Phosphate esters are the most common fluid used in EHC in power turbine control systems. However, many other types of fire-resistant fluids may be used in other applications. All being not compatible with each other, special care should be taken when changing from one fire resistant fluid to another.