[Rubensgt40]

Hi y'all

At a trade show recently, a competitor of Wagner's inferred that the Rapid RH probe will go out of calibration once the first (post-72H ERH) reading is taken.

They were referring to subsequent readings taken to map drying progress, in the days and weeks following the F2170- compliant reading. That is, read, cap the probe, ride off into the sunset... then return. Obviously this is a handy practice for larger projects.

Any teeth to this, or is it just a misleading use of terminology?

[CCR]

Terminology is new to me. Sounds like a jealous competitor trying to sway you over to their system. Run away and don't look back!!!

[Rubensgt40]

Oh I don't doubt that. Their system is quite good, at least up to current ASTM spec. But I have wondered about the accuracy of the rapid RH probe over repeated use. I'm sure it's fine, but doesn't hurt to play devils advocate occasionally to see what Jason's take is!

[eaadams]

It is easy to test isn't it....

One probe in now.
One probe in later.
Compare.

Repeat under different conditions and drying environments.

I will say I just got an IFTI report back and it had 3 equipment malfunctions (no reported %) on it out of 12 tests. aka 25%. I do not believe they use Wagner.

[CC Solutions]

Let's get Jason's thoughts.

I'd like to know if the probe's permeability is calibrated to allow the concrete below the probe to dry at the same rate as the rest of the slab.

Was this considered during the design? I understand we can drill a hole, let the concrete equilibrate and take a reading, but if you leave the hole wide open it will dry faster than if you cap the hole. What we really want (if we are trending the concrete moisture) is the hole to dry at the same speed as the rest of the slab. I don't know if we have thought that far into the process.....

[eaadams]

Reference the tape over hole discussion also.

[rapidrhrep]

@Rubensgt40 Sorry for the delay in responding, I have been off for a couple of days. Regarding calibration, this is a typical response from a competitor. Calibration relates directly to multiple usage, in multiple holes, and in multiple environments. When you are constantly reusing a sensor in these various environment, there is a potential calibration issue. The NIST traceable certificate that comes in the Rapid RH sensor packs is your necessary documentation of calibration within ASTM specifications. Regarding the second part of your comment that the competitor is ASTM F2170-11 compliant, please take a look at this video and verify that the manufacturer is TRULY within design compliance. http://www.youtube.com/watch?v=iX-s7dGkC4o

@CC the potential for the issue you are speaking is theoretically possible. One of the changes to the ASTM standard was to have ALL product sleeves go from top to bottom. The thought was, by doing this, you take away the potential for the hole to dry differently due to an exposed surface.

Thanks,

Jason

[Rubensgt40]

Thanks for that Jason. I wasn't sure whether "calibration" might include a probe...how do I put this.... "going off" like a tub of cream . I imagine if the hole is re-sealed, it is in an un-changeable environment and that's the whole point of calibration. I'll PM you about the competitor's equipment because I'm curious about that.

Correct me if I'm wrong JD, but I assumed your point was relating to the portion of slab immediately below the probe having the upward passage of RH "blocked", so to speak, and drying slightly different to the surrounding slab? is this the "edge effect" spoken of in F2420 (where they recommend taping a 3' x 3' sheet surrounding the insulated hood)? I never quite understood the "edge effect", guess I shoulda asked the question in Chicago.

Interesting point, but surely such an effect below a Rapid RH probe would be of negligible difference...

[CC Solutions]

(07-25-2012, 08:59 PM)Rubensgt40 Wrote:  Correct me if I'm wrong JD, but I assumed your point was relating to the portion of slab immediately below the probe having the upward passage of RH "blocked", so to speak, and drying slightly different to the surrounding slab?

Exactly.... Obviously if you plug the hole with a rubber stopper it will retain moisture. Conversely if you leave the hole open you will dry the slab out at the 40% deep hole you drilled.