Steve Wassenaar, Owner of Austates Pest Equipment, shares some technical tips and advice on how to execute concrete slab injection work right every time.
It’s pretty simple, right? Drill the hole and pump in the termiticide. All very straightforward… except when it’s not.
The fact is, every site will vary and to ensure an under-slab termite treatment is delivered as accurately and evenly as possible, there are a number of considerations that come into play. Choice of equipment becomes vital to success in dealing with these site to site variations. At Austates we decided to deal with the ‘except when it’s not’ scenario and developed the Deluxe Slab Injector to provide the control and flexibility to inject accurately under a wide range of situations.
In this article, we won’t be dealing with the assessment of sites for suitability of slab injection, or the drilling process. We’ll just focus on the actual injection of the termiticide and hopefully raise a few points that might not have previously been considered, or may have been forgotten. And give a few helpful tips, too!
Proper use of the pressure gauge
The biggest challenge when injecting through concrete is ensuring the appropriate dispersion of fluid under the path or slab. That starts with ensuring that the correct volume of termiticide is applied through every hole. So, as a pressure gauge (main picture, above) measures pressure, not volume, how can it be of any benefit?
It’s an invaluable tool in the absence of a flowmeter. Start by establishing the pump pressure you wish to work at (we would normally recommend between 30-70 psi or 300-500 kPa) but as the tech, that’s your call, and any termiticide label directions will take precedence. Connect your injector and note the pressure on the injector gauge with the trigger off. With the nozzle fitted, note the pressure with the trigger open (if you don’t have a flowmeter, you can make a note that this is the point at which the open flow begins). You now have an upper and lower pressure as a reference.
If you are injecting a hole and the pressure is at the lower limit, you know that the fluid is free- owing, and your timing method will be as accurate as it can get. If the pressure rises to the upper limit, it means there is nothing owing (remember this was the pressure with the trigger closed) and you may have a blind hole, or very heavy clay underneath. If the gauge reads in between, you will have to judge how much longer to stand there to ensure adequate volume in that hole.
There are, however, many factors that can make the timing method unreliable, such as a build-up of sediment occurring in a filter, or a slight blockage in a fitting of snap connector, slowing the ow. Another thing to consider is the amount of hose still on the reel. A hose that is rolled onto a reel will restrict ow more than a hose that is reeled completely out and laying straight. So if you calibrate your timing method at the back of the ute while the hose is nearly all rolled onto the reel, it is going to be different when you have moved all the way around the house, with most of the hose lying on the ground.
Another issue is the tip size. You will need to time each different diameter tip separately, and note the pressures.
The value of a flowmeter
Using a flowmeter is by far the most accurate method of ensuring a consistent delivery of termiticide per hole. Unlike a gauge, it does actually measure volume. So if you are subject to any of the variations listed above, which cause problems with the timing method, they won’t cause problems provided you have selected the correct flowmeter.
You need to ensure the flowmeter can read to the upper and lower limits of your flowrate. By that, I mean that some flowmeters may have a minimum flowrate of say 10 L/min, so if you are using a small diameter injection tip through tile grout, you may only be owing at 4 L/min; your flowmeter will read inaccurately, or not at all. The meter we recommend can read down to 1 L/min.
The shut-off valve is located at the bottom of the injector to reduce dripping. It helps ensure you don’t leave drip trails, which can concern clients, especially in sensitive accounts such as childcare facilities and nursing homes.
Defector cup, sealing cork, and footplate
The defector is a simple device that helps the tech reduce his/her chronic exposure, and also makes clean- up easier if there is a leak while injecting. (Have you ever injected a path in front of a glass sliding door and had this happen?) Hole-sealing corks are manufactured from a polyethylene grade that finds the middle ground between being hard enough to last and soft enough to seal effectively. The footplate allows additional pressure to be applied to the cork to allow sealing.
Lateral spray injection tips
By coincidence, I was lucky enough to be present at a house many years ago when the external paths were being dug up with a small excavator. It was educational, as I could see several subterranean trails adhered to the bottom of the path slabs that were originally poured straight onto the dirt. The soil had subsided under them about 50 mm in some places, and it reinforced the benefits of using injection nozzles with laterally dispersing spray that also angles upwards.
Under-slab soil treatment can be vastly improved by applying the termiticide through the nozzle while it is positioned at various heights in the hole. A range of injection nozzles is available from 4.8-9.5 mm to suit holes from 6-12 mm diameter, and standard lengths up to 500 mm.
It can be tricky to find a slab injector that offers all of these functions outlined above. About 25 years ago, we at Austates decided to create just such a model. The Deluxe Slab Injector is the go-to piece of equipment that gives pest managers the confidence they can inject the termitcide accurately under a wide range of situations. Available with an optional digital flowmeter, it is a tool that ensures you execute concrete slab injection work in the most thorough and professional way possible.