I've recently been put in- charge of reviving a Fume Suction System installed at the electroplating section of factory. After my stint in the army my engineering skills leave a lot to be desired, even though i am a Mechanical Engineer (by education not profession) so it is my request to PFers to help me out. The Electroplating Tanks are of dimensions 1510mmX750mm on top, they are meant for electroplating with chromium, lead, nickel and various other toxic chemicals that emit highly toxic fumes when the dc current is switched on. The shop floor has been arranged in two parallel section with nickel and allied tanks numbering 1 to 4 on one side(Side A). Chromium, lead and other tanks numbering a 1 to 7 on the other side(Side B). Im attaching a layout and a few pics. On Side A On side A, a common duct of dia 300mm is fitted in such a way that it runs paralled to the breadth of all four tanks(for about 35 Metres) and it is at height of about 3 metres from ground. Smaller ducts descend from the common duct in pairs and are fitted to the sides of the tanks along it's length. These smaller ducts have slits in them for suction. The bigger common duct is connected at it's terminal end to an Induced Draft fan for suction, driven by a 10 HP motor. Side B Side B is similar to side A, only difference is that it has Seven tanks and the common duct has a telecscopic dia with a dia of about 450 mm for two tanks and from thereon 300 mm dia for the remaining 5 tanks. Induced draft at it's terminal end is driven by a 15 HP motor. Now the exhaust of both Sides A and B is connected to a common duct which then goes into a Fume Scrubber. The problem is that inspite of powerful motors for the suction, the suction produced at the tanks is very miniscule. i) How can I Calculate the amount of suction I need to produce at each tank powerful enough to suck all the air and fumes surrounding the tanks. ii) How do i measure the amount of suction actually being produced at the tanks right now. iii) I need to understand weather the system designed and in place right now has been correctly designed or it just a stab in the dark.