Reusable or Single-Use? Which Rapid RH Sensor is For You?

Smart Systems, Smart Sensors, Smart Choices is more than just a clever-sounding tagline; it represents a new way of thinking with the Rapid RH®. With the introduction of the 5.0 reusable Smart Sensor, Wagner Meters is also introducing the concept of Smart Choices: Customers should be able to choose which model is the fastest, the easiest, and the lowest cost per test for their particular situations.

As you’re considering the options, it may help to run through a comparison of single-use and reusable relative humidity (RH) sensors.


Rapid RH® L6 Smart Sensor

Even though the L6 is referred to as “single-use,” it is not removed or discarded after taking a sensor reading. Once placed in a test hole, the Rapid RH® L6 Smart Sensor is neither removed nor unnecessarily handled and is always equilibrated. The sensor continues to be functional, and moisture conditions can be monitored over an extended period of time if desired.


  • Most accurate and lowest cost per test when compared to calcium chloride (MVER) and other RH testing methods. The L6 can save more than 100 hours of labor and wait time over the less accurate MVER test.
  • Fastest model for RH testing. There is very little site prep required for this sensor. Once the test hole has been drilled and cleaned out, the sensor is placed in the hole, covered, and allowed to equilibrate, or acclimate. Once equilibrated, the reading is taken and recorded, then the hole is covered. If the slab is not ready, test readings can be repeated, without having to go through the process of placing sensors, equilibrating, etc. Time savings are built into the L6; there is no cleanup, no calibration checks, and no time spent removing the sensor.
  • Easiest model to use for ASTM F2170 compliance. Each test location has its own sensor, which comes with a NIST-traceable certificate of calibration. If paperwork is not your thing, the L6 removes the need for calibration checks and extensive record-keeping. Just record the location of the sensor on a test location map, then file it in a safe place with the NIST-traceable certificate of calibration that came in the box with the sensor, and your compliance paperwork is done.

Who might benefit from the L6 single-use?

  • If you believe that “time is money,” the L6 is likely the sensor for you. This sensor gives you the fastest, most accurate measurement of moisture conditions, allowing you to move on to the parts of your business that actually generate income for you.
  • If you don’t do a lot of concrete moisture testing, you should probably consider using the L6 when you need to test. ASTM F2170 requires reusable sensors to undergo annual recertification of their calibration, and you’ll need to add that cost into your cost-per-test calculations. If you aren’t doing many tests in a year, you could end up spending more per test for reusables than for the single-use L6.
  • Large jobs: Even with extremely affordable pricing on the reusable Rapid RH® 5.0, the cost of a reusable sensor inventory large enough to eliminate leapfrogging could be prohibitive.

Free Download – Which Rapid RH Sensor is Right For You?


Rapid RH® 5.0 Smart Sensor

Most people involved with concrete moisture testing are familiar with reusable sensors. As you’ll see in the following list, there are a number of disadvantages to conventional reusable sensors. After discussing the pros and cons, we’ll show you how the reusable Rapid RH® 5.0 Smart Sensor was designed to eliminate those disadvantages.


  • Cost per test goes lower every time the sensors are used. Buy the sensor once, and use it as many times as you wish (keeping in mind the annual recertification requirements noted below).


  • Additional time and labor costs: Obviously, the reusable sensor will have to be removed from the test hole, and stored for future use. A larger concern is the ASTM F2170 requirement that a sensor must undergo a calibration check within 30 days prior to any testing. This can take 1-3 hours per sensor.
  • Higher cost of equipment: Reusable sensors are more expensive than single-use, and many contractors will purchase a small number of sensors, then leapfrog them on larger jobs. Unfortunately, this also leads to skipping the equilibration step, which significantly reduces test accuracy.
  • Yearly recertification or replacement requirements: As mentioned above, ASTM F2170 requires reusable sensors to undergo annual recertification of their calibration or replacement with a newly certified sensor, so that cost must be factored into any cost-per-test or ROI calculations.

The reusable Rapid RH® 5.0 Smart Sensor eliminates most of the major disadvantages of reusable RH sensors:
Rapid RH 5.0 Smart Sensor

  • Lengthy calibration checks: Each 5.0 comes with its own EasyCare CalCheck — a protective base integrated with a consistent RH generator. The sensor is stored in an optimal environment, always equilibrated, and always ready for an instant calibration check.
  • Affordable pricing/leapfrogging: The initial cost of investing is now low enough that it’s possible to have a larger inventory of reusable sensors, removing the need for leapfrogging.
  • Be sure to check out the Rapid RH® annual recertification program.

Who might benefit from the 5.0 reusable?

  • Testing services: If you offer testing services, reusables make sense. The new time-saving features of the 5.0 will save you much more time and money.

Frequent testing, especially for larger jobs: If you do a lot of testing in the course of a year, then the reusable allows you to drive your cost per test to the absolute lowest possible and still retain accuracy. Also, the initial cost of inventory is low enough to remove any need to leapfrog sensors. Now you can afford to have all of the sensors you need to get the job done in one pass.

Does a Single-Use Sensor Make Sense for Me?

There’s been a lot of buzz around our new reusable Rapid RH® 5.0 Smart Sensors, and rightly so. The 5.0 reusable has game-changing technology that reduces the time, labor, and initial investment costs of using reusable relative humidity (RH) sensors to about as low as they can go.

So why would anyone want to stay with a single-use sensor? The answer is: It makes possible an RH test that requires no maintenance – zero. For you, the Rapid RH L6 (now replaced by the L6) remains the standard for fast, easy, highly accurate and low-cost concrete moisture testing.

One of the greatest values in the Rapid RH L6 is its simplicity of use and effortless compliance with ASTM F2170. Each Smart Sensor can be used directly out of the box. A NIST-traceable certificate of calibration comes with each Smart Sensor pack direct from the factory. Using the 4.0 EX single-use sensor is a simple process:

Rapid RH Single-use or Reusable Choice

  1. Drill the hole
  2. Insert the Smart Sensor
  3. Let the sensor equilibrate in the hole
  4. Take the RH reading with our Easy Reader using our Touch-n-Sense (patent pending) technology

Done. That’s all you ever have to do to use our single-use sensors. You never need to run a calibration check. You never need to get the sensor re-certified. The single-use sensor just stays in the hole, ready and waiting for you to take a reading.

Single-Use Doesn’t Mean One-Time Use

This is a good place to clear up a common misunderstanding. Some people may be hesitant to buy a single-use RH sensor because they think it means the sensor can only be used once to provide a single reading at one point in time. Not true.

The L6 is “single-use” because it can only be used in one test hole. That hole becomes the single-use sensor’s permanent home. Once you insert that 4.0 EX sensor into its test hole, you can go back to it time and again to get additional RH readings.

Free Download – 4 Reasons Why Your Concrete Is Taking Forever to Dry

Bottom Line Decision

When you look at your current moisture testing method, what’s your reaction? Is conducting moisture testing in concrete what your business is all about, and you’ve been looking for an accurate, yet manageable and cost-effective reusable RH sensor? Then, by all means, check out the 5.0 reusable sensor.

Are you a flooring or general contractor who’s happy with how the single-use Rapid RH L6 works for you? Then stick with it. You won’t find an option that’s easier or more accurate than the L6 for measuring the moisture condition of a concrete slab.

Rapid RH Red or Orange SensorAre you still using the old calcium chloride test? Don’t let fear of ASTM F2170 requirements keep you from using the more reliable RH testing method. We designed the single-use Rapid RH 4.0 EX system with you in mind.

The L6 makes complying with ASTM F2170 completely hassle-free. A NIST-traceable certificate of calibration comes with every L6 Smart Sensor pack and is your assurance of proper calibration. In addition, using any one of our time-saving data collection tools (such as the DataMaster™ App) will simplify collecting, storing, and reporting the required data.

Be sure to also check out our companion article, “10 Guidelines for ASTM F2170 Concrete Testing and Preparation.”

Bottom line: If using the easiest, most hassle-free method to conduct a concrete moisture test is what makes sense for your business, then the single-use system is the choice for you.


The Rapid RH® Smart Sensor L6 remains the standard for fast, easy, and low-cost concrete moisture testing. The new reusable Rapid RH® 5.0 eliminates the problems inherent in conventional reusable sensor design. Rapid RH® now has the Smart Choice for any application.

You choose.

Last updated on October 3rd, 2023

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