Hood cleaning is one of the few businesses left that is completely dominated by small "ma and pop" businesses. The majority of the hood cleaning businesses out their have all the best intentions in performing honest hard work. I mean who wouldn't want to associate their name with the gold standard. So the big question that many of us have, seems quite puzzling. "Why is my exhaust system still greasy after the exhaust hood cleaning?"
We are going to address that question in a little bit. Before we do if you use a hood cleaning company that leaves a mess behind, not properly cover equipment or food prepping stations, or if they do not put a protective coat on shined or buffed hoods than fire them quickly! If these small tasks are not meet on each cleaning the chances are slim to none the exhaust system is cleaned! I can not stress that fact enough. If you recall one of those scenarios above than go pull a filter out of your hood, get a flashlight, and check to see how clean your duct work is. Exhaust hood cleaning is not meant to keep your kitchen appearance up! Hood cleaning is fire prevention! That's right fire prevention. Kitchen fires usually start with equipment that has malfunctioned. The kitchen suppression system will extinguish the fire on the equipment if it was installed correctly (check NFPA Code 96). The big problem is that the suppression system will not discharge until the plenum (the start of restaurant duct work right behind the filters) reaches between 360 and 520 degrees Fahrenheit! Wow do you feel nervous yet? Here is the deal if the exhaust system/duct work has been neglected and not properly cleaned the suppression system will not put out the fire in the duct work! This is a nightmare. One minute the facility has a small equipment malfunction and the next minute the building is on fire. Yes the facility will most likely be destroyed. At least this is not common...right? Wrong every year there is billions of dollars in damage from restaurant fires due to neglected exhaust systems!
So why do so many companies not clean the duct work in the exhaust system properly?
It is simple. You can not clean most restaurants with a steam producing power washer and hood cleaning chemicals alone like most people have convinced themselves to think. Yes the pressure washer and hood cleaning chemicals are a vital part of the operation but it is virtually impossible to get direct access in most duct work with a pressure washing wand no matter how hard you try. Why? The pressure washing wands are not 10 to 25 feet long like the average duct work is in an exhaust system. In fact the largest wands that can handle hood cleaning chemicals is 6 feet long. Every hood cleaning company needs and extendable magnetic duct scraper and a duct spinner. These two items make it possible to have direct cleaning access to the whole system. Lack of knowledge is no excuse. Any hood cleaning company who gets an exhaust system cleaned to bare metal will have all of the above tools.
The magnetic duct scraper will grab your duct with a powerful earth magnet. On both ends of the duct scraper is a 4" razor that will cut through all the grease as far down as 40 feet from one direction. Once the scraping is done the company will need to remove and wash down the small remaining grease. They will need to attach a duct spinner to a pressure washing hose. The duct spinner has two pressure washing tips that spin at a high rate of speed in a circle. This will be slowly dropped down the duct from the roof washing out the remaining nooks and crannies.
Make sure to find a company that offers after pictures of your exhaust system to let you audit the work. Companies that offer this service generally cost a bit more but they are worth every penny. Take into consideration the catastrophic events that could happen. And now that you have a little inside knowledge in the field make sure you set some time aside to call your current company and audit your system. 5 minutes could save the restaurant.