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Slide 1. Welcome to this module on pH, and the importance of pH monitoring of metalworking fluids. Slide 2. In this module, we will look at the following. The pH scale, and what pH is. The importance of pH monitoring. pH strips. Measuring pH. And what to do if the pH is low. Slide 3. This chart shows the pH scale. The pH scale is a scale of 1 to 14. 1, is highly acidic. 14, is highly alkaline, and 7 is neutral, for example. Water has a pH of 7. Acids and alkalis are opposite to each other, and acids react with alkalis. On this scale, there is a range which is generally acceptable to the skin, around the middle, not too extreme on either end of the scale. At very high acidity, and very high alkalinity, skin burns, and irritation can occur. The ferrous corrosion protection is generally in the alkaline pH range. The additives used to provide this protection are alkaline. If the pH value drops, then it is a sign that there are not enough ferrous corrosion additives in the system to prevent corrosion. Bacteria tend to grow, and thrive at slightly lower pH levels. Bacteria don’t like the high alkaline environment. As soon as the pH level drops, the conditions become more pleasant for them then, and they can grow very rapidly. In addition, as part of their metabolic process, bacteria give off acid by products. Therefore a drop in pH, can cause bacteria to thrive, and then, once there is a bacterial infection the pH can drop rapidly. For these reasons, metalworking fluids are designed to operate, and be maintained at a pH of just above 9, in the alkali region. This ensures good ferrous corrosion protection, and reduces the risk of bacterial infection. Slide 4. It is very important that the pH of metalworking fluids in use are monitored regularly, to check for signs of any contamination, to maintain the fluid in a good condition, and to prevent bacterial infection, ferrous corrosion, and fluid breakdown. The recommended pH limit for the specific fluid will be provided by the fluid manufacturer. FUCHS Lubricants, always provide the recommended pH limits on the fluid management charts. It is very unusual that the pH of the fluid will increase naturally, they normally naturally drift down if left untouched, or not topped up. If the pH is high, it could be a sign of contamination. For example, Cleaning fluids. In this case, you should check for any potential sources of the suspected contamination. The pH of a metalworking fluid can naturally drift down over time, in use, as the fluids additives get used up, and as the concentration drops. Therefore, it is very important to maintain the fluid at the correct concentration, this will ensure the correct amount of additives are in the system, to provide protection. If the pH is low, this could be a sign of bacterial infection, or could increase the risk of ferrous corrosion. This can lead to fluid breakdown, gummy deposits, ferrous corrosion, and ill health. The regular monitoring of pH is required by the HSE under COSHH. Slide 5. The pH of a metalworking fluid should be measured at least weekly. It is a very simple test to carry out, and ideally, trained operators should be able to carry this out daily. It is important that all results are recorded for COSHH and Health and Safety compliance, the HSE may want to see them if there is ever an inspection. The simplest method to measure pH is to use test strips, which change colour according to the pH value. As with all test strips, these should have a best-by date. If the test strips are too old, they can provide inaccurate results, due to colour fading, or distortions. An important aspect of using test strips is the correct procedure. The test strip should be dipped into clean emulsion, and not through floating tramp oil, because this can lead to measurement errors. It is also important to consider your safety. The working area must be safe and the metalworking fluid, easily accessible. Slide 6. To carry out the test: 1. Take a fresh, in date, pH test strip from the packet, taking care not to touch, and contaminate the coloured test part. 2. Dip the coloured test part of the strip into a suitably clean sample for a few seconds. Note, there is usually an instant colour change. 3. Remove the test strip from the sample, and shake off any excess fluid. 4. Compare the colour to the chart on the packet, and record the result. Also note, there are many different suppliers, and types of pH strips, so always refer to the original packaging for colour charts and instructions. Slide 7. To summarise, a low pH can cause a variety of problems which include. Increased bacterial activity. Emulsion instability. Corrosion. Gummy deposits on machines. Offensive odours. These can lead to operator ill health, fluid contamination, and machine breakdown if left unattended. If the pH is low, the pH can be increased by adding more product to raise the concentration, or by adding a pH booster. Congratulations! You have now completed the module. Slide 1. Welcome to the bacterial contamination testing module. In this module we will cover the importance of carrying out a bacteria check, and how it should be carried out correctly. Slide 2. We will firstly cover the importance of testing What happens if there is bacteria in the metalworking fluid. How to do a dipslide test, and finally, how to record the results. Slide 3. Why is it important to monitor the bacteria in a metalworking fluid system? Firstly, a large amount of it will slowly eat away at the metalworking fluid additives, and eventually degrade our metalworking fluid. Think of it as if the metalworking fluid is the bacteria’s food, and eventually the metalworking fluid will not perform the best as it should. Most importantly, are the increased health risks associated with it. If the bacteria is not monitored, left neglected, or untreated for a long period of time, breathing in the bacteria will not be good for the operators health. Therefore, it is vital to make sure the monitoring is carried out and the metalworking fluid is treated accordingly. The testing, is a very simple test, carried out by using a dipslide, which will be covered in the following slides. The dipslides give you an indication of how much bacteria is within the system, and from that, we can determine what action should be taken accordingly. Testing can be carried out on a weekly basis. However, if you prove that you are within good control, with recorded results, the frequency can then be extended to monthly. It is very important to keep records of the bacteria checks. HSE can audit sites unannounced, and request a history of these results, in order to verify if you are complying to their guidelines, and being in control. Slide 4. Here, we have listed the consequences of poor bacteria control. Low pH. Coolant performance reduction. Corrosion. Foul odours. High bacteria levels. Fungal growth. Potential health concerns if left neglected. The image to the right shows a case of heavy fungal growth. Slide 5. How to use a dipslide. A dipslide has 2 sides to it, 1 side has a pink agar, and the other has a white agar. Agar is a jelly like substance, which is used to grow bacteria. The white side will grow bacteria, and the pink side will grow any fungi, or yeast present in the metalworking fluid. 1. Wearing nitrile gloves, remove the slide from the plastic sleeve. Do not touch, or breathe on the dipslide, as this will produce false readings. 2. Dip the dipslide into the fluid. Ideally, avoiding any tramp oil. If possible, under a running metalworking fluid feed would be the optimum sampling point. 3. Give the dipslide a swirl in the fluid, and replace into the sleeve. Label the sleeve with a permanent marker, with the date, and machine ID. Place in an incubator for 48 hours, at approximately 30 degrees centigrade. Always refer to the manufactures instructions. Slide 6. After the 48 hours, reed the white side of the dipslide, and compare the results to the chart provided. Do not remove the dipslide from the sleeve, as the dipslide may contain bacteria, and is now classed as a biohazard, and always wear nitrile gloves when handling the dipslides. When recording the results, the unit used for bacteria is CFU per millilitre. Which stands for colony forming units per millilitre of sample. We need to focus the top row of figures 10^2, 10^3,10^4 and so forth. These are numbers that need to be recorded. Simply match the amount of red dots you see on the dipslide to the image of the chart. This will then tell you the level of infection, or CFU per millilitre for your metalworking fluid. For example, If a dipslide has a reading of 10^3, this will indicate that the sample contains 1000 colony forming units of bacteria, within 1 millilitre of sample. Slide 7. Though it is important to get a representative sample for testing, it is more important that you take it safely! Always adopt best practice, as highlighted in the picture, only take a sample of running metalworking fluid if it is safe to do so. Slide 8. Evaluation of the bacteria results from the dipslides? The HSE have set guidelines on what corrective action to take. If the bacteria reading is 10^3, or less, no action is required, and continue to monitor. If the bacteria reading is between 10^4 and 10^6, action is required. Add biocide to the system. We currently use Acticide 14 as a biocide, but it should only be used by a fully trained technician! Do not attempt to add biocide if you have not had the correct training. If Biocide is not readily available, another option, will be to clean out the metalworking fluid tank, and replenish with fresh fluid. This is usually advised if bacteria is problematic within metalworking fluid systems. Slide 9. For further information, please refer to HSE guidance on bacterial activity within metalworking fluid.