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  • Luminometer RLU standards

    Hey everyone,

    We just started playing with a luminometer. Today I soaked a PRV in ~1,000 ppm peracetic acid for 40 minutes. The meter read 58 RLUs when I swabbed it. Soaked for another 15 minutes - 110 RLU. Another 15 minutes - 78 RLU. The manufacturer recommends treating anything over 30 RLU as a fail. For those of you using a luminometer, do you have standards?

    Thanks.
    --Dean Brundage
    Owner / Unscrambler of Eggs
    Blake's Steaks Sandwich Shop
    (650) 823-3389

  • #2
    Over 30 is a fail in any standard, some places will reject anything over 20, bear in mind that the luminometer detects ATP, that is a molecule present in organic matter, so if you soaked the PRV without cleaning it, it might be sanitized, but the organic matter remains adhered to the valve, hence the high reading.


    Sent from my iPhone using Tapatalk

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    • #3
      I am trying to figure out pass/fail thresholds as well, so if you found anymore info please pass it along.

      I know that if you test after sanitation, you can get false readings because certain sanitizers/acids interfere with the detector. It is recommended to test after cleaning and rinsing.

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      • #4
        We test everything after a CIP and rinse. If the tank was opened we swab. If it was cleaned under pressure we test rinse water. Anything 3 and under is a pass. Anything over 3 gets retested. After the retest, anything under 10 is a pass, 10-30 will depend on circumstances, 30 and above needs CIPed again. In my experience using one, there usually isn't a middle ground, it usually either passes right away to needs CIPed again/futher investigation.

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        • #5
          I've been thinking about bringing a luminometer intp our process. Do you guys have any specific models you wpuød recomend? The ones I've seen so far have been really expensive. But hey, if thats what it takes, so be it. Lunimoneters are cool.
          Marius Graff,
          Head Brewer, Graff Brygghus
          Tromsø, Norway

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          • #6
            What circumstances will let you pass a 10-30 vs. failing it? Wouldn't you just change your cleaning regimen to get it under 10? Also, why do you have the under 3 and then the under 10 checkpoints? Thanks in advance for any answers you can provide as we start picking control points in our brewery.

            As far as models, we went with the Hygiena EnSURE and use Aquasnap for rinse water collections and Ultrasnap Total for surface testings. It was about $1500 for the luminometer and $200-220 for a case of 100 swabs.

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            • #7
              Under 200 RLU = pass

              We use a Kikkoman Luminometer. Under 200 RLU is a pass, i.e. clean. After cleaning we lock up the tanks until next use and sanitise with peracetic acid immediately before next use.

              We test tanks in three places (inside tank wall, rinse water and outlet butterfly valve).

              Outlet butterfly valve is the usual place to fail.

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              • #8
                Originally posted by Yeastman View Post
                What circumstances will let you pass a 10-30 vs. failing it? Wouldn't you just change your cleaning regimen to get it under 10? Also, why do you have the under 3 and then the under 10 checkpoints? Thanks in advance for any answers you can provide as we start picking control points in our brewery.

                As far as models, we went with the Hygiena EnSURE and use Aquasnap for rinse water collections and Ultrasnap Total for surface testings. It was about $1500 for the luminometer and $200-220 for a case of 100 swabs.
                We use this unit as well. Aquasnaps and Ultrasnaps. Test after clean and rinse and then run a sanitize cycle for good measure.

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                • #9
                  The ATP meter uses an enzyme-based detection scheme to measure the amount of ATP. The effectiveness of the enzyme is affected by pH and redox potential. Pretty much everything used to clean or sanitize will have an extreme of either pH or redox potential, so you should expect that residual cleaners or sanitizers will cause incorrect and varied test results.

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                  • #10
                    As above, residue of some sanitisers can give rise to false-positive results with ATP measurement. This is most likely to be the reason for the apparent increased readings, after cleaning.

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                    • #11
                      forrestmz3005 is correct, need to clean not just sanitize before testing.

                      i like/agree with scarne78's procedure.

                      we will test tanks after a caustic and acid washes are complete by checking a final rinse water.

                      that being said there are times where i've tested rinse water and got a high number only to rinse again and get a zero. always recheck, better safe than sorry.

                      also there are times i've cleaned a brite under pressure got a zero on the rinse, opened the tank and found all kinds of organics around/under the manway gaskets or cleaned a fermenter and got a zero but found crud on top of the spray ball....

                      THERE IS NO SUBSTITUTION FOR A GOOD VISUAL INSPECTION (when possible)

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                      • #12
                        Originally posted by ibrewforyou View Post
                        forrestmz3005 is correct, need to clean not just sanitize before testing.


                        also there are times i've cleaned a brite under pressure got a zero on the rinse, opened the tank and found all kinds of organics around/under the manway gaskets or cleaned a fermenter and got a zero but found crud on top of the spray ball....

                        THERE IS NO SUBSTITUTION FOR A GOOD VISUAL INSPECTION (when possible)
                        Yeah. All this is right. There's a big danger of "false negatives" with RLU meters if you're just testing rinse water. If for some reason the spray ball is not wetting all of the tank, the rinse water will only show you the state of the area that is getting wetted not the part of the tank being missed which could be filthy.

                        I think the RLU meter is more helpful for the discipline it imposes on the general cleaning regime rather than any guarantee about the cleanliness of individual tanks. Other things being equal, you know that if you have a regular cleaning regime that returns low RLU values and you sanitise clean tanks prior to use, you generally aren't going to have problems with infection, but it's no guarantee.

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