Culligan M1 Series Installation, Operation And Service Instructions page 42

the product water flow may have been due only to a decrease in temperature or pressure, in which case cleaning would
not be indicated.
If any change in the performance of the elements was not due to a change in operating conditions, it may be time to clean
the elements. In general clean the elements:
1. When the product flow rate decreases by 10% (or when the feed pressure must be increased by 10% to main-
tain the same product flow), or
2. When the percent of rejection decreases below specification.
NOTICE Because strong chemicals are used to clean the elements, maintenance cleaning is not recom-
mended. If the elements need to be cleaned frequently (more than twice a year), the pretreatment
may be inadequate. Obtain a current water analysis and test the Silt Density Index and the Total
Chlorine level of the water on-site to review what changes in pretreatment may be needed.
When cleaning is required, the type of material which is fouling the element should be identified, if possible. Refer to
Table 5 to determine the possible causes of the performance change.
Percent
Rejection
Low Hardness Scale
High Silt or Biofouling
For example, if the product flow is low but the percent rejection is normal, the likely causes of the problem are silt or
biofouling. Please note that if the product flow rate has increased (with no increase in temperature or pressure) the likely
reason is damage to the membrane, which cannot be repaired by cleaning.
Once the foulant has been identified, choose the recommended cleaning chemical(s) from Table 6.
Membrane Problem
Hardness Scale
Iron
Silt
Biofouling
Because phosphoric acid can be used by itself or in combination with sodium hydroxide to clean almost all types of fou-
lants, it is generally recommended over hydrochloric acid when choosing a "stock" acid.
NOTICE Some municipal surface water supplies are treated with alum. Aluminum fouling results in low flow
and, occasionally, in low rejection. If aluminum fouling is suspected, use only hydrochloric acid.
Use a pH meter to prepare acid and caustic solutions, and to monitor pH changes as the solutions react with any foulants.
Materials required:
1. Solution tank (50 gallon capacity, minimum), to prepare and store the chemical solution.
2. Tank stand, to elevate solution tank to level above pump.
3. Tubing 1/2" O.D. to connect cleaning adapter ahead of Pre-filter.
4. A pH meter.
5. A pre-filter cartridge (P/N 00955004).
Before proceeding record the "NOW" values in
38 Culligan® M1 Series Reverse Osmosis
Low
Hardness Scale (light) or Iron
Table 5. Performance change possible causes.
Table 6. Recommended membrane cleaning chemicals.
Table 4.
Flow
Normal
—
Cleaning Chemical
Hydrochloric acid, phosphoric acid
Hydrochloric acid, phosphoric acid
Phosphoric acid and sodium hydroxide
Phosphoric acid and sodium hydroxide
High
Membrane Damage
Membrane Damage (light)
38 Cat. No. 01022940