NSF/ANSI 58 System Type Clarification for Contaminant Reduction testing

Sun Young Lee (COWAY)

2014. 5. 14

Issue

NSF/ANSI 58 groups ROs into 4 categories:

RO systems can fall under multiple categories and it

is unclear which section has priority, which can lead

to issues with consistency when testing an RO

system.

1. Systems with storage tanks and automatic shut-off.

2. Counter top systems with storage tanks or reservoirs.

3. Systems without storage tanks.

4. Systems with no shut-off provisions

2/7

Example

+

Plumbed in countertop non-pressurized tankautomatic shut-off

Type 1

Systems with storage tanks

and automatic shut-off

Type 2

Counter top systems with

storage tanks or reservoirs

or

ASO

Pre-filter

RO

Post-filter

Feed water

Drain

3/7

Main difference between type 1 and 2

- Sampling requirements for day 1

- Procedure for determining the DPR and efficiency for the RO

The characteristic permeate flux behavior

in type 1 & 2 system

1 2 3 4 5 6 7 8 9 10 11 12020406080100120

Time

Flow

RO Permeate

1 2 3 4 5 6 7 8 9 1011121314024681012

Time

Flow RO Permeate

Type 1 Type 24/7

Example

Proposal

Type 1 should be used for systems with pressurized

storage tanks and automatic shut-off. Regardless of

whether they are under the sink, counter top, or other.

Type 2 should be used for systems with non-

pressurized or open to atmosphere tanks or

reservoirs and automatic shut-off. Regardless of

whether they are under the sink, counter top, or other.

5/7

Proposed Changes

Current:

Systems with storage tank and automatic shut-off

Proposed:

Systems with pressurized storage tank and automatic shut-off

Affected Sections:

6.9.7.1, 7.1.2.7.1, 7.1.3.5.1, 7.2.1.6.3, 7.2.2.6.3, 7.2.3.6.36/7

Proposed Changes

Current:

Counter top systems with storage tank or reservoir

Proposed:

Systems with non-pressurized storage tank or reservoir and automatic

shut-off

Affected Sections:

6.9.7.2, 7.1.2.7.2, 7.1.3.5., 7.2.1.6.1, 7.2.2.6.1, 7.2.3.6.17/7