Sampling Locations

UFC 3-240-13FN

25 May 2005

limited or if high silica is suspected.

6-3.3

Sampling Locations. Typical locations for water sampling points in a

steam boiler system are shown in Figure 6-3. Each sampling point has a separate

cooling coil. Two or more sampling points are not connected by a single manifold to the

same cooling coil because it is almost impossible to determine if one of the valves has a

leak that might contaminate the sample being taken. Guidelines for sample collection

are provided below.

The makeup water sample does not have to be cooled. The sample

location typically will be the output of an ion exchange unit or some other

water-softening unit.

The boiler feedwater sample is a combination of makeup and condensate

return. An appropriate location for sample collection is from the discharge

of the boiler feed pump. This will be a hot sample, so a cooling coil is

used. Alternatively, sample collection for feedwater can be from the low-

pressure deaerator outlet.

The boiler water is very hot. Collect this sample from the continuous

blowdown line between the boiler and the regulating valve if possible. You

may collect it from a gauge-glass connection, if necessary. Use of a

cooling coil is recommended.

The steam condensate is hot. For small systems, collect this sample from

a line that enters the deaerating heater if possible. For medium and large

systems, you may need to collect condensate samples at two or more

locations in the system to obtain sufficient data for calculation of the

proper treatment level. When attempting to find a leak, you may need to

collect condensate samples from various locations in the system. Use of a

cooling coil is recommended.

Steam is collected regularly for systems with high-quality steam

requirements like those with turbines and those meeting NAVSEA steam

quality requirements. Otherwise, steam samples are rarely collected.

Refer to the ASME Performance Test Code (ASME PTC 19.11, Steam

and Water Sampling, Conditioning and Analysis in the Power Cycle, for

sampling procedures.

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