GE P&W OS7785 User Manual

CorTrol* OS7785

Oxygen Scavenger

• Controls oxygen corrosion

• Provides superior metal conditioning for feed-

water and condensate systems

• Improves boiler reliability

• Contains no hydrazine or derivatives of hydra-

zine

• Contributes no inorganic solids to feedwater

Fact Sheet

2

(>1000 psig) [70 kg/cm
water solids are a major concern.

CorTrol OS7785 contributes no inorganic dissolved
solids to the system, which may result in a reduc­tion in boiler blowdown with corresponding energy
savings.

] applications where boiler

Description and Use

CorTrol* OS7785 is an aqueous blend of an organic
oxygen scavenging compound and a neutralizing
amine. This product is a rapid and highly effective
oxygen scavenger, and does not contribute to inor­ganic boiler water solids. In addition, it is safer to
handle than hydrazine.

CorTrol OS7785 is designed for the control of corro­sion caused by dissolved oxygen in makeup, con­densate, and feedwater systems. It is not suitable
for use where the steam directly contacts food per
FDA 21 CFR 173.310 or USDA Section G6. It is ap­proved for use where steam contacts paper or pa­perboard used in food packaging per FDA
21CFR176.170 and 176.180.

Typical Applications

Even with good deaerating heater operation, suffi­cient dissolved oxygen can remain in the feedwater
to damage the boiler system. Even low levels of dis­solved oxygen are critical to high-pressure (high
temperature) systems. Oxygen in water produces
pitting which is particularly severe because of its
localized nature. Economizers and feedwater heat­ers are particularly susceptible to oxygen attack.

While it can effectively be used in low-pressure
boiler systems, CorTrol OS7785 was specially devel­oped as an oxygen scavenger for higher pressure

Figure 1: Comparison of CorTrol OS7785 and hydrazine for

The oxygen scavenging efficiency of CorTrol
OS7785 is better than hydrazine (see Figure 1).
Because it is such a strong reducing agent, CorTrol
OS7785 has also demonstrated the ability to reduce
certain forms of metallic oxides, thereby condition­ing metal surfaces (see Figure 2).

Because CorTrol OS7785 is an excellent oxygen
scavenger and provides superior metal conditioning
at typical condensate temperatures, the product is
highly desirable for condensate system protection.

CorTrol OS7785

removing dissolved oxygen.

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* Trademark of General Electric Company; may be registered in one or more countries.

©2009, General Electric Company. All rights reserved.

AM-FSbCorTrolOS7785_EN.doc Sep-09

Treatment And Feeding Requirements

Without With
CorTrol OS7785 CorTrol OS7785

Figure 2: CorTrol OS7785 promotes the reduction of iron

from the red, nonmagnetic state (Fe2O3) to the
black, magnetic state (Fe3O4). As a result, iron
removal with an electromagnetic filter can
increase from approximately 50 percent to over
95 percent.

Feed Point - CorTrol OS7785 should be fed continu-

ously to the deaerator storage section or to the fe­edwater line. For condensate protection it can be
fed diluted to the steam header or to condensate
lines.

Feedrate - Feed CorTrol OS7785 based on the boiler
feedwater dissolved oxygen level. Feed continu-
ously.

Dilution - Use good quality condensate, demineral­ized water or deaerated feedwater to make a con­venient feeding strength. The material may be
diluted in any proportion. Mild agitation should be
provided for initial mixing only. Product solution
should have minimum exposure to atmospheric
oxygen. If this material is fed from a day tank, it is
recommended that only a 24-hour supply be made
at a time.

Equipment - Feed CorTrol OS7785 using a mild
steel feed system. This product is suitable for use
with PaceSetter* automated chemical feed and
control equipment.

General Properties

The use of CorTrol OS7785 is beneficial where fe­edwater is used for attemperation. When feedwater
containing an inorganic oxygen scavenger is used
for attemperation, harmful deposits on superheater
tubes and/or turbines may result. CorTrol OS7785 is
also beneficial in petrochemical plants as it does
not affect sulfur-sensitive catalysts.

CorTrol OS7785 can also be used for boiler layup.
Follow the recommended procedures for boiler and
superheater storage and feed at a minimum of
2000 ppm [mg/L] CorTrol OS7785 in the boiler water

3

(16.7 lb/1000 gal [2 kg/m

] of boiler water). If the
boiler is fired during storage, supplemental pH ad­justment may be required. Neutralizing amines or
ammonia should be used to keep the boiler water
pH above 10.0.

Physical properties of CorTrol OS7785 are shown on
the Material Safety Data Sheet, a copy of which is
available on request.

Packaging Information

CorTrol OS7785 is a liquid blend, available in a wide
variety of customized containers and delivery
methods. Contact your GE Water & Process Tech­nologies representative for details.

Safety Precautions

A Material Safety Data Sheet containing detailed
information about this product is available upon
request.

Page 2 Fact Sheet