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SOLVING FOR DH UNITS FOR TANK INTERIORS?
Solving for the DH Unit question requires 2 simple Steps – both requiring some fairly simple math.
The 2 steps are:
1. Determining how many cubic feet are in the tank.
2. How many air changes do you need.
STEP 1
Involves an old high school geometry formula for volume of a cylinder.
Remember this one? Volume = Π r2h
So, in the client’s example, his 60-foot diameter means a radius of 30 feet. We plug that into the formula 3.14 for PI, 30 for the radius and 67 for the height…and we end up with 189,342 cubic feet of air space.
V = Π r2h
V= 3.14 x (30×30) x 67
V = 3.14 x 900 x 67
V= 189, 342 ft3
We’ll need this number for Step 2.
STEP 2
Requires knowing how many air changes per hour are needed.
BlastOne always recommends you have around 4 Air Changes per hour when you’re doing DH to hold the blast, so you don’t have to prime as soon as you’re finished painting.
The final equation involves taking the volume of air we got in Step 1 and dividing it by 60. 60 is the number of minutes in an hour, which give us the CFM (Cubic Feet Per Minute) we need to ventilate. We then multiply that by the number of air changes we want per hour, which in our example is 4.
DH UNITS
Volume/mins
x # changes
189,342 / 60
x 4
3,155
x 4
12,620 DH UNITS
And there you have it, roughly 12,600 cubic feet per minute of DH Capacity for this particular tank. Which means if the units are 6,000 each, two units should effectively give you dehumidification in this tank and compressor fed air.
Please note: This is a general rule of thumb and as always, if you have a complicated or uncommon situation always seek expert advice.
