Establishing a quantitive measurement of the total moisture content of a given sample can in some cases be essential for diagnosing a damp problem and understanding whether a sample is dry. When a quantitive measurement is preferred and a destructive technique is not an issue, there are a couple of testing options available. One well-established option is the Protimeter Speedy 2000 Tester, commonly known as the calcium carbide test.
The Protimeter Speedy Moisture Tester is essentially a container manufactured from cast aluminium and fitted with a calibrated pressure gauge. The vessel uses calcium carbide which can accurately test samples, even when they have been contaminated by hygroscopic salts which bewilder electronic moisture meters. The calcium carbide produces acetylene gas which builds a pressure within the vessel which can be viewed on the Speedy meters pressure gauge. The pressure increase is proportional to the amount of water in the sample.
In this review I will be looking at the Protimeter Speedy 2000 Tester S2000D model. I will give my experience of using the meter as well as the realities of handling the hazardous substance which is the calcium carbide reagent.
The process of producing calcium carbide was invented in 1892. Early uses for calcium carbide was in carbide lamps which were used in early vehicles and mining lamps. The method of using calcium carbide for measuring moisture was seemingly mentioned first in 1906 by P.V. Dupré.
According to http://www.gracesguide.co.uk, Thomas Ashworth & Co were established in 1828 and were manufacturing the likes of railings, gates and cable making machinery from 1922. They later became an instrument maker and aluminium and zinc diecaster which is where the speedy meter comes into play. The earliest reference to the speedy meter is in a written advert published in September 1947 although the meter itself would have been invented some time before this. Thomas Ashworth & Co became a subsidiary of Bruco Dean in 1961 and has changed hands over the years. Fast forward to today and Amphenol Advanced sensors sell the Protimeter Speedy Moisture Meter.
As you can see from the old advert, the design of the meter has not changed over the years. The accessories and carry case have seen the main modernisation with the introduction of the electric balance and hard plastic carry case. However, the little measuring scoop remains the same from what was used in the 40’s, I think the mantra here is not to fix it if its not broken.
The Protimeter Speedy 2000 Tester S2000D comes with the following:
- Protimeter Standard Speedy Moisture Meter
- Electronic weighing scales with Batteries
- Waterproof and Shockproof Carry Case with High-Density Foam Insert
- Bristle Scour Brush and Soft Cleaning Brush
- Cloth and Spare Speedy Cap Washer
- Measuring Scoop and Measurement Cups
- User Instructions
The first impression when opening up the set is the carry case which is hefty in weight (around 5.5kg) and very serious looking with its fire warning label plastered on the front. The handle has a rubber grip which makes the case easy to lift with a secure grasp. The two clasps securing the case have a satisfying push button opening mechanism. Within the case the items are all held in place with the same quality high density foam which is so familiar throughout the Protimeter range of products. The softer top foam provides a reassuring feel that the products will not be damaged when closing the case or transporting the meter around.
The electronic scales are super simple with two buttons on the front along with a small display. The base has a lock button and the slot which houses the three AA alkaline batteries.
The meter itself has a completely solid and robust feel. The swing top fastening lid weirdly reminiscent of the old swing top Grolsch lager bottles. The weighty cold metal feel giving the meter a sense of durability. The pressure gauge is located at the base of the meter with clear discernible writing.
Before using the kit, I read through the manual and carefully considered the health and safety implications. For this reason, the review has taken me much longer to compile than any other review I have completed to date. I decided to gather some basic PPE and safety equipment to allow me to safely carry out the testing procedure.
In my opinion, a thorough risk assessment should be completed with guidance from the material safety data sheet to allow you to decide on appropriate measures to put in place to mitigate any risk from hazards. The PPE I ordered was just for the purposes of the review and would likely evolve if I was using this equipment on a regular basis.
I ordered the following safety equipment:
- Powder fire extinguisher
- Disposable gloves
- FFP3 Disposable Masks
- Safety goggles
- Disposable coverall
I also ordered items for the storage of the unused calcium carbide and to aid the collection of samples for testing which included:
- Empty 5L paint can (to store the calcium carbide)
- Plastic funnel
- 35mm plastic film canisters (which could be attached to bottom of funnel)
I also ordered up some calcium carbide which I will discuss later on in the review separately as this is a topic worth going over in some detail.
Using the kit
When all of my equipment had arrived, I was then ready to complete a test of a few samples. For this I chose to use high density cement block with varying degrees of moisture. I tested over three days and progressively subdued the block to more water each time with the final test taking place after having the block submerged in water for 6 hours before testing.
Before I started the testing, I first considered storage of the calcium carbide. The carry case has a cut out which perfectly houses a 500g tin but I purchased an empty paint can so I could store it separately if needed. I cut out some polystyrene and placed it into the paint can and this held the calcium carbide tin securely within it. My Garage is dry and well ventilated so this is where I decided to keep the reagent within its secure tin within a sealed can. For me this was a more than suitable arrangement for the purposes of the review. This is not for the storage of spent samples, careful consideration will need to be given to spent samples which I will touch on later.
I set up my working area, donned my PPE and prepared the equipment to complete the test. Prior to drilling into the block I checked the block with the Protimeter Surveymaster pinless moisture measurement function. The block was showing as wet with a score of 220 on the electric meter.
I followed the test procedure on three consecutive days and the results were as follows:
Day 1: 0.5%
Day 2: 1.25%
Day 3: 2.5%
I was expecting a higher percentage than 2.5% for a saturated block however this may be perfectly normal for this type of high density material.
I noticed that the scale was very precise and with the model of meter I had, only a 6g sample was required which struggled to reach the 10ml line on the beaker. When shaking the meter after adding the reagent I did feel that I could accidentally damage the delicate gauge dial but after three tests everything seemed fine.
Cleaning the vessel proved to be an issue each time even when using the brushes provided with the kit. I feel like the brushes were not quite adequate to fully clean out the vessel. This was compounded by the fact that the inner surface of the vessel is slightly textured and that the mouth of the container is curved making the sample reluctant to empty. With the sample dust and the carbide dust I felt the spent waste was difficult to empty without releasing dust into the air.
For the final test I noticed the securing cap screw was becoming a bit stiff so I eased this off with some WD-40. As the third test involved a wetter sample I noticed the gas hiss out of the vessel when emptying after the third test.
On the whole the test procedure is fairly quick, I spent more time cleaning up and preparing for the test than actually completing the test procedure. Although I was expecting higher results, the meter was clearly working by showing a gradual increase in percentage with each test.
The Calcium Elephant in the Room
Some say the destructive nature of a moisture test using the speedy meter is the main disadvantage of this technique but for me it is the use of calcium carbide, by far. I will try my best to lay out the reasons for why I feel this is the case.
Before testing the equipment, I decided to reach out to the Scottish Environment Protection Agency to see if I could gain some advice on the disposal of spent samples of calcium carbide. Unfortunately, they could not provide any useful advice and asked me to contact my local authority. My local authority said that they could not help and that they would not accept samples of calcium carbide, a specialist would need to dispose of the samples.
At this point I was feeling a bit frustrated as I had never realised that a substance that is so easy to obtain is so difficult to dispose of. After calling three specialists waste disposal companies I found one who would accept an uplift but they asked me whether it was calcium carbide or calcium carbonate I needed to dispose of. Calcium carbide being much more expensive to dispose of.
From what I gather, calcium carbide when mixed with water leaves you with calcium hydroxide (slaked lime) and acetylene gas. Carbon dioxide from the air will carbonate the calcium hydroxide to produce calcium carbonate. This process can take some time to occur, potentially several weeks as the lime hardens as it carbonates.
I have had prominent individuals reach out to me and say that spent carbide reverts to calcium carbonate and is totally inert. They believe as this is the case, it is therefore not a controlled waste product when all the gas has reacted out of the sample. This may be true but it ignores the fact that calcium hydroxide takes time to carbonate and when a sample is mixed with damp plaster or mortar it will not be fully reacting. The problem with surveyors who place a spent sample in the bin thinking it has reverted to calcium carbonate are with more likely disposing of a sample with a mixture of calcium carbide and calcium hydroxide.
So, we have established that disposal of calcium carbide is an ongoing concern for the regular use of this meter as organising a special uplift after every test would not be economical. This leaves an interesting quandary which leaves plenty of food for thought moving forward.
My next concern is granularity of the calcium carbide which is commonly sold to surveyors. In the safety sheet it states that the ‘handling of dust-free, lump formed calcium carbide is not considered to be a health risk when safety precautions are taken.’ When I looked up lab technicians using calcium carbide, it seems they use a larger grain size that what I was sold. The calcium carbide I have is a dust-like substance with a 0/1mm grain size which I was completely unaware of until it arrived.
The tiny granular composition of the calcium carbide regularly sold to surveyors would seem to me to present a higher health risk. Just so I can make it abundantly clear for people considering handling calcium carbide, some of the hazards include:
- Contact with water releases flammable gases which may ignite spontaneously
- Skin irritation
- Serious eye damage
- May cause respiratory irritation
- Acute poisoning if inhaled
There would not be any significant inhalation health hazard if I had been sold dust-free lump formed calcium carbide. Why is the small grain version the most readily available type of calcium carbide? It seems to me that the Scientific Laboratory Supplies (SLS) calcium carbide is the larger grade type although I am unsure if they sell to private individuals.
There is also a larger grain carbide contained within individually sealed glass vials from Radtke Messtechnik. The glass vials are entered into their meter and broken inside when conducting the test, this sounds like a very interesting method of using the reagent with the meter which involves less contact from the user.
The problem that Protimeter face is that the new grade of calcium carbide reagent yields lower percent moisture content measurements when compared with the original grade. The devices will be calibrated to the particular grade of reagent so its not as easy as swapping out one type for another as it would falsify your results.
My issue for the general user is that when you google ‘dust-free lump formed calcium carbide’ nothing really shows up. I purchased my calcium carbide from a surveying equipment seller who are the top result when searching for this reagent. There is nothing on their website which suggests whether it was dust free or lump formed and it turns out I had to deal with the dusty variety.
Practical information on the safe storage, handling, transport and disposal of calcium carbide seems to be scarce. I have contacted various agencies and industry professionals and it seems there is no clear good practice, certainly not that I could find. Whilst the material safety data sheets are useful they cant be confused as constituting a workplace risk assessment.
I am left with a sense of disappointment as I was really looking forward to using the speedy meter, this was probably compounded by my naivety around the reality of using calcium carbide. I had seen people online and respected surveyors alike dealing with calcium carbide in a fairly blasé and care-free way with no PPE to be seen. Possibly I am catastrophising the actual risk at play here but I do not feel that I am.
Protimeters Speedy 2000 Tester itself is a stellar device and one with a long and successful history. It is one of the only ways to obtain quantitative data on the moisture content of a sample and for this reason many surveyors will continue to use the calcium carbide test.
On the meter itself, I have next to no major issues. Its easy to use, from the scales to the reading of the percentage wet weight. Unfortunately, it’s impossible to separate the meter from the use of the reagent which by reading this conclusion might read as rather pessimistic.
Some surveyors may decide that using the off-site gravimetric test method as a safer method as well of having the benefit of being able to distinguish between hygroscopic moisture and total moisture. This method obviously has its own disadvantages as well like the space to house the equipment and time to complete the test.
I am not by any means trying to over egg the dangers of calcium carbide but I do need to take the safety guidance seriously and the reality of how seemingly difficult it is to get rid of.