Spritzer Start-up / Shut-down & QC Procedures
At Foam Supplies, safety is always our primary concern, especially personal safety. That’s why we created this instructional video on the proper and safe startup, shutdown, and QC procedures of our spritzer dispensing unit. After viewing the procedures, if there is anything you don’t understand please contact our technical service department before attempting anything. A representative will be happy to walk you through procedures, or schedule a visit for training. Before we begin, let’s take a quick look at the various letter and color designations of the isocyanate. Commonly referred to as MDI, or iso for short, and polyol cylinders in different parts of the world. In this video, we’ll also use the US designations of A for iso and B for polyol. Okay, let’s get started. First, always remember to wear protective eyewear and gloves while operating the gun.
Please refer to the SDS for the proper and safe handling of materials, including the use of protective equipment like safety glasses, protective gloves, and respirator protection where needed. A separate video is available on proper respirator use. With your protective gear in place, you’re ready to begin the startup procedures. The first step is to check the chemical cylinders to ensure sufficient chemical supply. For large vessels, check the level gauge on both the ISO or A and polyol or B cylinders. If the chemical level is five percent or below, cylinders must be changed before proceeding. Draining tanks below five percent will lead to nitrogen in the chemical lines. For smaller vessel types, we recommend investing in scales to get accurate readings and to allow for maximum utilization of the chemical in the tanks. If you do not have scales, the next best method is to carefully push the vessel, as if you were going to tip it over. If the vessel is not easy to tip, sufficient chemicals exist. If the vessel tips easily, it is recommended that you change it out.
When the chemical level draws lower than the chemical dip tube, nitrogen is pushed into the chemical lines. Nitrogen in the lines will cause problems with dispensing equipment, and can also result in bad foam, and therefore poor in product. If you need to change chemical cylinders, follow these procedures. First, double check that the nitrogen cylinder is secure. After disconnecting the old cylinders, remove the cap from the new is or A cylinder, and clean out the old. Attach the hose, or strap and tighten with a wrench. There is no grease on the polyol, or B cylinder, so just remove the cap. Lubricate the threads and attach the hose. Now check the temperature gauges on both filter assemblies. Proper operating temperature is important for all polyurethane applications, but is especially critical for spritzer applications. 85 degrees Fahrenheit or 29 degrees Celsius is the minimum operating temperature. Conditioning tanks to the minimum temperature must occur prior to all other procedures. Please refer to the process setup acknowledgement for the specific operating parameters for your foaming process.
Next, confirm there is sufficient nitrogen supply. This is a good time to review the ways nitrogen is supplied. Single bottles, six packs, 12 packs, micro bulk tanks, and bulk tanks. Only approved nitrogen regulators that are equipped with a pressure relief valve can be used to assure safe operation. Check with your FSI representative if you have any questions. To check the supply, open the nitrogen cylinder valve slowly, but ensure that it is fully open. Now, connect the nitrogen hoses to the ISO and polyol cylinders. Slowly open the nitrogen ball valves at both cylinders to pressurize. After the cylinders are pressurized, slowly open the chemical ball valves at the cylinders. Now, check the following three parameters. First, check for leaks. Leaks will lead to an unnecessary waste of nitrogen and cause more frequent change outs. Second, check the nitrogen reserve gauge.
Sufficient nitrogen capacity is necessary for production. The minimum nitrogen requirement is 250 psi. Change nitrogen tanks when the gauge shows reading below 250 psi. Third, check the nitrogen pressures. Keep in mind these pressures are set during initial setup, and adjustments rarely if ever need to be made. For most applications, the ISO pressure should be 30 to 50 psi lower than the polyol pressure. For example, an ISO pressure of 150 psi and a polyol pressure of 180 psi is ideal. However, for marine applications the pressure difference should be reversed, with ISO pressure of about 180, and polyol pressure of about 150. Again, pressures are preset and rarely need to be changed.
Next, clean the gun head face and attach the ratio nozzle. Then, open the iso and polyol ball valves at the gun whip. At this point, it is important to remember that the gun is ready to fire and precautions should always be taken to avoid an accidental discharge. Before production, it is important to perform two quality control procedures, ratio, and throughput. First, check the chemical ratio. Having the proper ratio is critical to dispensing good foam. Ratio is the weight comparison for the is or A output to the polyol or B output. As an example if the ISO weight is 124 grams, and the polyol weight is 91 grams the ratio is 100 to 73. Which is ideal for a system with a polyol target ratio range
of 100 to 70 to 75, which is typical for flotation foam. If the ratio dropped below 100 to 70, the info would be Iso rich. If the ratio rose to over 100 to 75, the foam would be polyol rich. If the ratio is not correct, poor foam qualities will result. Iso rich foam can be crunchy, have glassy cells, and result in less yield. Polyol rich foam can be soft and spongy, can shrink and can also result in less yield. Ratios are system specific and provided upon initial setup. If you’re not sure of the proper ratio for your system please contact FSI technical service for assistance.
To check the ratio, make sure the ratio nozzle is attached and taped two separate plastic bags together, and slide them over the independent ends of the nozzle, so that only Iso chemical dispenses into one bag, and only polyol into the other. Once you have a firm grip on the bags, disengage the trigger safety, and pull the trigger to dispense a timed 6 second shot. Then seal both bags. You are now ready to weigh the chemical and calculate the ratio. Remember, you only want to record the weight of the chemical itself, not the box or plastic bag. So you will need to tear or zero out the scale with an empty plastic bag.
Remove the empty bag and place the bag of ISO chemical on the scale and record the weight in the daily log. Remove the ISO bag and replace it with the polyol chemical bag and record the weight. Now, divide the polyol by the ISO to calculate the ratio. In this example of a phone system used for insulation, the iso weighed 118 grams and the polyol weighed 107 grams. Using the ratio formula, Divide 107 by 118 then multiply by 100 which results in a ratio of 10 to 90.6. Record this value in the B ratio column of the daily log. In this example, the ratio is within the target range of 100 to 88 to 92. If the ratio is in the desired range, you can move on to the throughput procedure, but if the ratio is not in the desired range, call the FSI technical service department, adjustments may be necessary. It is important to properly dispose of the two bags of chemical used for calculating the ratio.
Simply dump the contents of one bag into the other and mix the two chemicals thoroughly. This foam can now be allowed to cure, and then be safely discarded. Do not place the foam in a dumpster or trash can until the bag has had 24 hours to cool down. Now you are ready to check throughput. We define throughput as the weight of the foam dispensed from the unit per min. Commonly referred to as pounds per minute, or ppm. Attach the production or mixed nozzle. For this demonstration, we are using a standard mixed nozzle, the nozzle used for marine applications is slightly longer. Dispense a timed 6 second shot into a plastic bag. While the foam is setting up, detach the production nozzle and wipe off the gun face thoroughly. Then, weigh the bag and record the weight in the daily law. In this example, the foam weighs 167 grams. Since we won a pounds per minute value, multiply the weight of the six second shot by 10 to obtain a 60 second or one minute equivalent. In this example, we calculated a value of 1670 grams.
Next, divide that value by 454 to convert the grams per minute into pounds per minute. In this example, the throughput of our gun is 3.67 ppm. The ppm is acceptable if it falls within five percent of the target throughput configured at initial setup. If not, call FSI for technical support. Attach a new production nozzle and you are now ready to begin production. When dispensing is to cease for more than 30 seconds at a time, detach the mixed nozzle and replace it with a new one. Mixed nozzles cannot be reused. The spritzer gun whip was engineered as a disposable part and requires frequent replacement. When replacing the gun whip, start by shutting off the chemical valves on both the ISO and polyol cylinders.
Next, close the chemical ball valves at the end of the gun width. Then dispense the remaining chemical in the gun whip into a trash bag or receptacle. Disconnect the gun whip from the insulated hose assembly. We recommend doing this over a trash can or receptacle to catch a residual chemical that may frolf out as you loosen the connections. Discard the old gun whip. Wipe off any residual chemical from the insulated hose assembly to keep the equipment clean and in good working condition.
Attach the new gun whip and ensure the connections are tight. Repeat the process for the other gun whip. Then, open the chemical ball valves on both cylinders, and open the chemical ball valves at the gun whip. You will need to pull the trigger for about 10 seconds to purge the air from the new whips. Now, perform the ratio and throughput quality control procedures before continuing production. At the end of production, the spritzer dispensing unit must be properly shut down. Here’s a quick review of the procedures. First, engage the trigger safety on the gun and remove the mix tube, and wipe off the gun face. Now, close both the iso and polyol ball valves at the gun whip. Then clean the gun face of chemical and foam using DK 817. Lubricate the gun face and pack the handle with petroleum jelly, or lithium based grease.
Next, close the chemical and nitrogen ball valves on the cylinders. Finally, turn the nitrogen supply off. The spritzer gun is now properly and safely shut down. Laminated startup and shutdown procedures should be present in all designated mixing areas for reference. Please contact the FSI technical service department if you are in need of additional or replacement copies. Again if you have any questions at all about the spritzer startup, QC, or shutdown procedures, please call our technical service department at 1 800 325 4875. For international customers, dial + 1 314 344 3330. We’re always ready to help our valued customers in any way we can.