25 May 2005
Sampling and Testing of Makeup Water. The makeup water for boiler
systems, chilled water systems, and diesel engine jacket water systems usually comes
from an ion exchange unit or a dealkalizer.
The recirculating water from high-temperature water systems and from
systems that use the sulfite-caustic soda treatment program is tested once per day for
pH and sulfite (see paragraph 5-2.2.1).
Recirculating chilled water and hot water treated with the nitrite-borax or
molybdate programs is tested once per month for either molybdate or nitrite, depending
upon the chemical in use (see paragraph 5-2.2.2, 5-2.2.3 and 5-2.2.4). The system pH
is tested once per month and on the day following chemical additions.
Ion Exchangers and Dealkalizer Water. The recommended water testing
frequencies for these systems are summarized in Table 6-3, with additional information
Influent Water Testing. Ion exchange influent water is tested once per
week for total hardness. Dealkalizer influent water is tested once per week for total (M)
Effluent Water Testing. Effluent water from these systems is tested for
total hardness either once per day or once per shift (3 times a day) depending on the
frequency of regeneration; more frequently if the frequency of regeneration is excessive.
The appropriate frequency (cycle length) will depend upon feedwater hardness, bed
size, resin type, strength of regenerant, and flow rate.
Sampling Location. The location of the water sample point is an
important consideration for ensuring that a representative water sample is obtained.
Care must be taken to avoid collecting a sample that is a mixture of influent and effluent
water on ion exchange units that use automatic regeneration and multi-port valves.
Brine Testing. The brine used for regeneration is sampled periodically
and tested with a hydrometer to measure its strength. The sodium chloride brine should
be as near 100% saturation as possible (approximately 28% by weight) for efficient
WATER TESTING. Routine and appropriate testing of the system water is
an essential component of a water treatment program. Water testing provides
information that can be used: to ensure the protection of the water system equipment; to
prevent unexpected system failure; to provide information used to control water quality;
and to verify that water treatment chemicals are maintained at the proper concentrations
within the system or, if not, to allow for adjustment of their concentrations. An adequate
testing program requires proper recordkeeping of the data that are used for assessing
the effectiveness of the water treatment program. If testing data for the water quality
analyses are inconsistent with that expected for the treatment method being used,
determine the reasons. This determination can involve reanalysis and checking of the