Perkins 904J-E28T, Руководство по эксплуатации и обслуживанию, Страница: 96 / 152

Tableau 23
Acceptable Water
Property
Maximum Limit
Chloride (Cl) 40 mg/L
Sulfate (SO
4
) 100 mg/L
Total Hardness
170 mg/L
Total Solids
340 mg/L
Acidity pH of 5.5 to 9.0
For a water analysis, consult one of the following
sources:
• Local water utility company
• Agricultural agent
• Independent laboratory
Additives
Additives help to protect the metal surfaces of the
cooling system. A lack of coolant additives or
insufficient amounts of additives enable the following
conditions to occur:
• Corrosion
• Formation of mineral deposits
• Rust
• Scale
• Foaming of the coolant
Many additives are depleted during engine operation.
These additives must be replaced periodically.
Additives must be added at the correct concentration.
Over concentration of additives can cause the
inhibitors to drop out-of-solution. The deposits can
enable the following problems to occur:
• Formation of gel compounds
• Reduction of heat transfer
• Leakage of the water pump seal
• Plugging of radiators, coolers, and small passages
Glycol
Glycol in the coolant helps to provide protection
against the following conditions:
• Boiling
• Freezing
• Cavitation of the water pump
For optimum performance, Perkins recommends a
50 percent by volume of glycol in the finished coolant
(also referred to as 1:1 mixture).
Nota: Use a mixture that will provide protection
against the lowest ambient temperature.
Nota: 100 percent pure glycol will freeze at a
temperature of −13 °C (8.6 °F).
Most conventional antifreezes use ethylene glycol.
Propylene glycol may also be used. In a 1:1 mixture
with distilled or deionized water, ethylene and
propylene glycol provide similar protection against
freezing and boiling. Refer to Table 24 and refer to
table 25 .
Tableau 24
Ethylene Glycol
Concentration Freeze Protection
50 Percent
−36 °C (−33 °F)
60 Percent
−51 °C (−60 °F)
REMARQUE
Ne pas utiliser le propylène-glycol dans des concen-
trations supérieures à 50 % de glycol en raison des
capacités de transfert thermique réduites du propy-
lène-glycol. Lorsqu'une meilleure protection contre
l'ébullition ou le gel est requise, utiliser de l'éthylène-
glycol.
Tableau 25
Propylene Glycol
Concentration Freeze Protection
50 Percent
−29 °C (−20 °F)
Some commercially available coolants are based on
alternative fluids, such as 1, 3-propanediol (beta-
propylene glycol, PDO), glycerin (glycerol), or
mixtures of these alternatives with ethylene/
propylene glycols. At the time of publication of this
document no industry standard exists for coolants
based on these chemicals. Until such standard/
specifications are published and evaluated, use of
PDO, glycerine, or other alternative coolants are not
recommended in Perkins engines.
To check the concentration of glycol in the coolant,
measure the specific gravity of the coolant.
96 M0092609-04
Chapitre Entretien
Liquides conseillés