Math help? 

"AestheticsInMotion" (aestheticsinmotion) 01/31/2019 at 18:24 • Filed to: And yet I remember calculus and statistics....

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I’m making a nightly inspection form for work, and one of the tasks will be to fill a chemical tank in one of our roof-cleaning vehicles. I’m trying to find an equation for this so I can put it in my form and allow my employees to plug in how much roof mix is already in the tank, and then get numbers for how much of e ach component of the roof mix they need to fill the tank completely . In the past I’ve just done this in my head, but now that I’m training others to handle it I can’t seem to get myinternal method to transfer to an equation.

This should be simple, but I can’t recall basic algebra. Help?

Relavent info:

There’s a 90 gallon tank labeled “roof mix”. This is what my guys need to fill up every night.

The proper ratio for cleaning an asphalt shingle roof is 40% Sodium Hypochlorate to 60% water. So 1:1.5. There’s one other chemical involved, but it’s a negligible amount and added by hand so we don’t need to include it in the equation.

The amount of roof mix left over each day is variable. Sometimes the crews use it all, sometimes there’s 10 gallons left, sometimes there are 30 gallons left, etc.

I feel like I’m one of those people in the math books with the word problems.

Oh and because someone will probably ask... This is all being pumped in and nobody will be in contact with any of the chemicals. Even so, full face mask with chemical respirators , rubber boots, nitrile gloves and chemical-resistant clothing are required for my team. Safety!

ttyymmnn > AestheticsInMotion 01/31/2019 at 18:29

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Highlander-Datsuns are Forever > AestheticsInMotion 01/31/2019 at 18:31

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I s the tank on it’s side or is it upright, because that takes it from no problem to how much time do you have?

bob and john > AestheticsInMotion 01/31/2019 at 18:36

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X = How many gallons are left

90-X = y     y = gallons used

y/2.25 = z

Z = amount of Sodium hypoclorate in gallons
1.5( Z) = Amount of water in gallons

AestheticsInMotion > Highlander-Datsuns are Forever 01/31/2019 at 18:37

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Hmm.... I’m not sure what your getting at. But I have a lot of time!

The tank is as you see it below (the one on the right). Dropper tubes come in from the top and reach the bottom for both suction and discharge, both with filters, etc.

benjrblant > AestheticsInMotion 01/31/2019 at 18:39

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So, a known volume left in the tank, minus tank volume which equals the remaining volume. the remaining volume is split in a 1:1.5 ratio. did i get that correct?

90-[remaining volume of tank] = [volume to fill]
0.4 x [volume to fill] = sodium hypochlorate to add
0.6 x [volume to fill] = water to add

a formula for each fluid would be as follows, with X being the volume presently in the tank:
(90-x) x 0.4 = sodium hypochlorate to add
(90-x) x 0.6 = water to add

Highlander-Datsuns are Forever > AestheticsInMotion 01/31/2019 at 18:45

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Put marks on it like the other tank, then it’s 90 minus what ever is remaining (V). Then Water=0.6*V and NaOH=0.4*V.

Se also benjrblant. Circular tanks on their sides require calculus to calculate volume but these are not circular.

Patrick Nichols > AestheticsInMotion 01/31/2019 at 18:51

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How are you measuring how much how much is left in the tank? Does the Sodium Hypochlorate take up space or diss olve in the water? After that it is a pretty simple equation.

Cash Rewards > ttyymmnn 01/31/2019 at 19:06

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EXACTLY FOUR GALLONS!

First place I went, too!

AestheticsInMotion > Highlander-Datsuns are Forever 01/31/2019 at 19:06

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Couldn’t you just initially f ill the tank 10 gallons at a time (or whatever) and mark the side of the tank?

AestheticsInMotion > benjrblant 01/31/2019 at 19:12

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Thank you sir. It makes so much sense to see it, but I was having so much trouble getting to that point.

A bit more complicated... My company also cleans metal and tile roofs. These roofs use the same chemicals, but at a different ratio. For example, we use a 50:50 SH to water mix for metal roofs, and a 60:40 SH for tile.

So i f we had x gallons of roof mix (metal roof) left over from the day and needed 90 gallons total of roof mix (asphalt shingle) is there a way to change the above formula to account for that? 

Highlander-Datsuns are Forever > AestheticsInMotion 01/31/2019 at 19:13

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Yep! That’s what I would do, use a 5 gallon bucket.

AestheticsInMotion > Patrick Nichols 01/31/2019 at 19:13

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You can't see them from this angle, but the tank is marked every 5 gallons. For this application we don't need things to be the EXACT ratios, just close. 

AestheticsInMotion > ttyymmnn 01/31/2019 at 19:14

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Man, one of these days I need to watch die hard

VajazzleMcDildertits - read carefully, respond politely > Highlander-Datsuns are Forever 01/31/2019 at 19:16

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NaOHNeeded = (90-JuiceLeft) * .4
WaterNeeded = (90-JuiceLeft) * .6

My work (this is a completely clumsy and roundabout way to do what Highlander did in 2 lines.)

Also, I suppose the safety gear is if something goes completely tits up.
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JuiceNeeded =90-JuiceLeft

WaterNeeded = .6 * JuiceNeeded
NaOHNeeded = .4 * JuiceNeeded

.6 * JuiceNeeded + .4* JuiceNeeded = (.6 + .4) * JuiceNeeded = JuiceNeeded

WaterNeeded = NaOHNeeded * Ratio

.6 * JuiceNe eded = .4 * JuiceNeeded * Ratio

.6/.4 = 1.5 = Ratio

WaterNeeded   = NaOHNeeded * Ratio

WaterNeeded / 1.5 = NaOHNeeded

WaterNeeded + NaOHNeeded = 90-JuiceLeft = JuiceNeeded

WaterNeeded + WaterNeeded / Ratio = 90-JuiceLeft

WaterNeeded + WaterNeeded / 1.5 = 90-JuiceLeft

( 1.5 * WaterNeeded + 1 * Water Needed) / 1.5 = 90-JuiceLeft
2.5 * WaterNeeded = ( 90-JuiceLeft) * 1.5

WaterNeeded = (90-JuiceLeft) * 1.5 / 2.5

1.5/2.5 = .6

WaterNeeded = (90-JuiceLeft) * .6

NaOHNeeded = (90-JuiceLeft) * .6 / 1.5
NaOHNeeded = (90-JuiceLeft) * .4

Highlander-Datsuns are Forever > VajazzleMcDildertits - read carefully, respond politely 01/31/2019 at 19:18

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It’s like you just derived some bad ass formula for light speed or something but really it’s about the juice ratio. Hmmm.jpeg

VajazzleMcDildertits - read carefully, respond politely > Highlander-Datsuns are Forever 01/31/2019 at 19:26

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Honestly, it’s pretty embarrassing to see it written out and how stupid it looks.

I should have turned it into a python script or something to obfuscate it. 

Patrick Nichols > AestheticsInMotion 01/31/2019 at 22:03

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Oh so its just: gallons needed / 5 = x, 3x = water, 2x= mix

benjrblant > AestheticsInMotion 02/01/2019 at 11:05

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Yes, but this is a little more complicated. Swamped at work right now but I’ll get to this in a bit!

DirtyLaundry > AestheticsInMotion 02/01/2019 at 13:52

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I made you a quick and dirty spreadsheet calculator that will calculate how much h ypochlorate and water you need for a 90 gallon tank given a certain amount of leftover from the previous day. Change values in green to get output in red. Your guys can open it up on their phone to quickly calc volumes needed for X amount of tank capacity minus Y amount of leftovers.

https://docs.google.com/spreadsheets/d/1-cDDUgxMkrp5dTiM4_44JaZedrH1CtzSAEsIuCupqDg/edit?usp=sharing