1、 NSF Protocol P172 Sanitization Performance of Residential and Commercial, Family-Sized Clothes Washers August 2006August 2006 Copyright 2006 NSF International Page i NSF International, an independent, not-for-profit organization, is dedicated to public health safety and protection of the environmen
2、t by developing standards, by providing education and by providing superior third-party conformity assessment services while representing the interests of all stakeholders. This Protocol is subject to revision. Contact NSF to confirm this revision is current. Users of this Protocol may request clari
3、fications and interpretations, or propose revisions by contacting: NSF International Engineering Final Rule (Federal Register; August 27, 1997), rounded to the nearest pound. If the measured weight of the clothing Test Load differs from the nominal weight by more than 0.12 lb (50 g), adjustment of t
4、he Test Load weight is made by adding or removing hand towels. Test Loads shall be washed and disinfected before using in test runs to remove sizing, finishing agents, and residual bacteria. For example, if the actual design capacity of a horizontal axis washing machine is 3.4 cubic feet, DOE Table
5、5.1 indicates the average load size to be 8 lb. Table 2 of AHAM HLW-1 2006 indicates that an 8-lb clothes load would initially contain 13 hand towels, 4 pillow cases, and 2 sheets. If the Test Load weight differs from the nominal by more than the allowed tolerance, adjustment would be made using han
6、d towels. Note: refer to AHAM HLW-1-2006 for Test Load clothing item specifications, loading, conditioning, and age requirements. Soiling To simulate typical soil loading into the machine, Soiled Swatch strips shall be attached to the clothing load as described in Performance Evaluation Procedure fo
7、r Household Washers (ANSI/AHAM HLW-1). Refer to Section 5, Table 2 (for Horizontal Axis Washers) or Table 3 (for Vertical Axis Washers) of ANSI/AHAM HLW-1 for the number of soil strips to attach to each clothes load. August 2006 Copyright 2002 NSF International Page 7 of 10 Soiled Swatches are avail
8、able from Textile Innovators. (see Annex C). Detergent If detergent is used for the sanitizing cycle, the amount and type of detergent used in the cycle shall be determined by the clothes washing machine manufacturers instructions. If detergent is used, it shall not be antibacterial and shall not co
9、ntain bleach. Samples Test and Control Samples shall consist of 12 x 12 inch (30.5 cm x 30.5 cm) pieces of heavy weight blue denim material (14 oz/400 g weight) available from Textile Innovators Corporation (see Annex C) which are double-hemmed by folding up inch (1.3 cm) on each edge and sewn to pr
10、event fraying. The Test and Positive Control Samples shall be used to hold the inoculum of test organisms. New denim shall be washed 10 times prior to usage in testing to remove sizing, colorants, etc., and shall be used for no more than 25 test runs. Test Procedure Load Preparation and Sample Inocu
11、lation The Test Load, three Test Samples, three Positive Control Samples, and three Negative Control Samples, and all Soiled Swatches shall be autoclaved (121oC/250oF at 15 psi for 15 minutes) prior to use in the testing. The Test Samples and Positive Control Samples shall be inoculated individually
12、 (i.e. one challenge organism per Sample) with approximately 2 mL of the challenge organisms inoculum, achieving minimum target initial counts of approximately 106cfu/mL eluting solution. The inoculum shall be uniformly applied to the “right” side of the Test and Positive Control Samples by distribu
13、ting drops of inoculum along the hem-stitching and across the surface of the material with a dispensing pipette (1 - 5 mL capacity). Sample Extraction and Plating Technique Samples shall be extracted by placing Test and Control Samples into individual sterile plastic stomacher bags containing one li
14、ter of eluting solution (phosphate buffer water with 1% Tween 80) and pummeling for 10 minutes. Samples of eluting solution, with appropriate dilutions, shall be spread plated on appropriate media such as m-endo or VRB for K. pneumoniae, Mannitol Salt agar or Baird-Parker for S. aureus, and Pseudomo
15、nas Isolation Agar for P. aeruginosa. Baird Parker (Difco #0768-01-1), Pseudomonas Isolation (Difco #0927-01-9) and m-endo (Difco #0006-01-3) agars are available from a variety of vendors, including BD Biosciences (see Annex C). Plates shall be incubated for 48 - 72 hours at 35 - 37oC and counted. S
16、ize of sample is governed by expected bacteria density. An ideal sample volume will yield 30 - 300 cfu on a plate. Positive Control Sample Extraction and Analysis Within 15 minutes of inoculation, Positive Control Samples shall be extracted. The eluting solution shall be plated, incubated for 48 - 7
17、2 hours at 35 - 37oC and counted. If the eluting solution cannot be plated within the given time frame, it may be refrigerated at 4oC for up to 18 hours. August 2006 Copyright 2002 NSF International Page 8 of 10 Machine Cycle Within 15 minutes of inoculation of Test Samples, the Test Load, Test Samp
18、les, and Soiled Swatches shall be intermixed and loaded into the washer. Following manufacturers instructions, the designated cycle shall be initiated and allowed to run to completion. After removal of Test Samples, the dried Test Load and Soiled Swatches shall be autoclaved to remove any residual v
19、iable microorganisms. Test Sample Extraction and Analysis Within 45 minutes of the end of the washer cycle, individual Test Samples shall be sorted and extracted. The eluting solution shall be plated, incubated for 48 - 72 hours at 35 - 37oC and counted. If the eluting solution cannot be plated in t
20、he given timeframe, it may be refrigerated at 4oC for up to 18 hours. Test Evaluation Methods For each individual test run, the following calculations shall be made: Percent Reduction = (ACC ATC)/ACC x 100 Log Reduction = log ACC log ATC or alternatively log (ACC/ATC) Where: ACC = average Positive C
21、ontrol Sample organism count before cycle (cfu/mL) ATC = average Test Sample organism count after cycle (cfu/mL) Test Acceptance Criteria After a complete washer cycle, the levels of detectable bacteria on the Test Samples shall be reduced by a minimum of three logs (as compared to the Positive Cont
22、rol Samples) for each of the test organisms. August 2006 Copyright 2002 NSF International Page 9 of 10 Annex B Machine Sanitization Performance Test Test Purpose This test is to determine if a residential clothes washer will harbor any test organisms between laundry cycles when installed and operate
23、d in accordance with the manufacturers instructions. Test Procedure This procedure is designed to evaluate the possibility of carryover of the test organisms from one cycle to the next due to adherence to the interior surfaces of the washer or due to contaminated water remaining in hose lines. Befor
24、e each test run of the Laundry Sanitization Performance Test described in Annex A, a sterilized Test Load and three Negative Control Samples shall be placed into the washer and run through the shortest cycle at the lowest temperature setting (information to be provided by manufacturer). The test was
25、her and supply water shall be as specified in Annex A of this document, and no detergent shall be used. At the end of the cycle, the Negative Control Samples shall be removed and extracted with 1 liter of eluting solution, as described in Annex A of this document. This test shall be performed one ho
26、ur (10 min) before the Laundry Sanitization Performance Test described in Annex A. Test Acceptance Criteria After a complete washer cycle, the levels of detectable bacteria extracted from the Negative Control Samples shall be no greater than 10 cfu/mL for each of the test organisms used in the test
27、methods described in Annex A of this document. Decontamination Subsequent “decontamination” cycles can be performed using an empty washer cycle at 40 - 45C with 50 - 100 ppm bleach in the wash cycle until the test acceptance criteria of less than 10 cfu/mL is attained. The next test run shall not st
28、art until all Negative Control Samples have less than 10 cfu/mL for each of the test organisms. August 2006 Copyright 2002 NSF International Page 10 of 10 Annex C Test Material Information Type Cultures American Type Culture Collection 12301 Parklawn Drive Rockville, MD 20852-1776 AHAM Standard Mixe
29、d Loads (preconditioned) Textile Innovators Corporation 101 Forest Street, P.O. Box 8 Windsor, NC 27983 252-794-9703 Test Sample Swatches (blue denim) Textile Innovators Corporation 101 Forest Street, P.O. Box 8 Windsor, NC 27983 252-794-9703 Agar BD Biosciences 2350 Qume Drive San Jose, CA 95131-1807 Fax: 408-954-2347 Soiled Cloth Swatches Textile Innovators Corporation 101 Forest Street, P.O. Box 8 Windsor, NC 27983 252-794-9703
