CMS SOM App. H, Tag V196

6.2.5 Carbon adsorption (monitoring and testing frequency)

Testing for free chlorine, chloramine, or total chlorine should be performed at the

beginning of each treatment day prior to patients initiating treatment and again prior to

the beginning of each patient shift. If there are no set patient shifts, testing should be

performed approximately every 4 hours.

Results of monitoring of free chlorine, chloramine, or total chlorine should be recorded in a

log sheet.

Testing for free chlorine, chloramine, or total chlorine can be accomplished using the N.N-

diethyl-p-phenylene- diamine (DPD) based test kits or dip-and-read test strips. On-line

monitors can be used to measure chloramine concentrations. Whichever test system is used,

it must have sufficient sensitivity and specificity to resolve the maximum levels described in

[AAMI] 4.1.1 (Table 1) [which is a maximum level of 0.1 mg/L].

Samples should be drawn when the system has been operating for at least 15 minutes. The

analysis should be performed on-site, since chloramine levels will decrease if the sample is

not assayed promptly.

Interpretive Guidelines § 494.40(a)

ANSI/AAMI RD52:2004

5.2.5 Carbon adsorption

In addition to removing free chlorine and chloramine, carbon also adsorbs a wide variety of

other substances, including both naturally occurring and synthetic organic compounds. The

capacity of carbon to remove free chlorine and chloramine may be reduced when other

substances “mask” reactive sites on the carbon media. Additionally, the efficiency of free

chlorine and chloramine removal is reduced as the pH increases or the temperature decreases.

The net effect of those variables is that the finite capacity of carbon beds to remove free chlorine

and chloramine cannot be predicted with any certainty. Therefore, their performance needs to be

monitored frequently.

6.2.5 Carbon adsorption

Carbon adsorption performance is monitored by measuring free chlorine and/or chloramine

concentrations in the water exiting the first carbon bed of a series-connected pair. It should be

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noted that sampling for total chlorine (the sum of free chlorine and chloramine), allowing a

maximum level of 0.1 mg/L of total chlorine, is often simpler than analyzing for free chlorine and

chloramine separately.

More frequent monitoring may be appropriate during temporary operation with a single carbon

bed, which can occur following breakthrough of the first bed. In such instances, testing is

performed on water exiting the second carbon bed in a series-connected pair. The decision to

increase the frequency of monitoring should be based on the system's past performance and

whether changes in feed water quality have occurred.

AAMI Rationale for the Development and Provision of This Recommended Practice

A.6 Monitoring

A.6.2.5 Carbon adsorption

Intensive monitoring of carbon adsorption beds is recommended due to the long history of

adverse events associated with chloramine contamination of dialysate. Chloramine

concentrations in municipal water can fluctuate from day to day, and the capacity of carbon

adsorption beds to remove chloramine can vary depending on the pH and temperature of the

water, the nature of the chloramine compounds present, and the presence of other substances in

the water. The dependence of chloramine removal on multiple factors makes the performance of

carbon adsorption beds unpredictable. Patient safety can only be ensured by intensively

monitoring the performance of the carbon adsorption bed. Configuring carbon adsorption beds

in series and sampling from a port located between the two beds provides one margin of

protection against chloramine breakthrough. When chloramine is first detected in the effluent

from the first adsorption bed, essentially the full capacity of the second bed remains available for

chloramine removal. This reserve capacity allows the user to conveniently replace the exhausted

bed without risk to patients. The exhausted bed is discarded, the second bed is moved into the

first position, and a new bed is placed in the second position. A new bed of virgin carbon shall

be used for replacement. Carbon cannot be regenerated in a dialysis facility, and the use of

regenerated carbon is prohibited by ANSI/AAMI RD62:2001 (see 2.3 in that AAMI document).

Backwashing of carbon beds does not regenerate the carbon, although it may allow more

efficient use of the bed’s capacity by removing channels that can form in the bed during routine

operation.

AAMI Rationale for the Development and Provision of This Recommended Practice

A.6.2.5 Carbon adsorption

The recommendation that the water purification system operate for at least 15 minutes before

sampling is to guard against inadvertently drawing water that has been in the bed for an

extended period.

Suggested monitoring guidelines from ANSI/AAMI RD52, Table 4, include:

For carbon adsorption beds, monitor the product water levels of free chlorine and/or total

chlorine between the beds prior to beginning each patient shift. The expected result is less than

or equal to 0.1 mg/L of total chlorine.

Additional Guidance:

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For parallel-connected tanks/beds, testing must be performed for each set of tanks/beds each

time testing is conducted.

Test strips with color comparison charts that indicate a low-level reading of zero and a first

“number” of 0.5 are not sufficiently sensitive to detect levels as low as 0.1 and should not be

used for testing product water for safe levels of chlorine/chloramine. An indication of “0” on the

comparison charts does not suffice to demonstrate that the strips are sensitive to “0.” Consult

the manufacturer’s guidance or contact the manufacturer if there are any questions regarding

the sensitivity of specific test strips. When deciding whether to use a “quantitative” or

“qualitative” test methodology, it is essential to recognize that determining low levels of

chlorine (i.e., <0.1 ppm) requires the use of the quantitative method.

If an online chlorine/chloramines monitor is in use that incorporates an automated alarm,

particular testing times are not required. Facility policy and practice should follow the

manufacturer’s guidance regarding any required comparison testing and calibration of the

monitor.

The ability to discern colors is a crucial job function for individuals responsible for interpreting

colorimetric tests. Depending on the test method used, staff assigned this responsibility must be

capable of properly interpreting the results and accurately distinguishing and identifying any

colorimetric results; alternatively, a digital meter must be used. If a digital meter is used, it

should be calibrated to zero before testing to ensure accurate measurements.

For deficient practices with exceeding the acceptable level of chlorine or chloramine refer to

V270-273 of this section.