Bouyancy of Sealed PVC Sched.40 Gray Conduit

They can support a weight equal to the weight of the volume of water they displace.

You need to calculate the volume on the outside diameter.

This in dm3 minus the weight of the pipe and everything you put inside is your buoyancy in fresh water. (density 1) In salt water you will have slightly more, depending on the salt content.

3.14 X d2 / 4 times the length (d2 is diameter quadrate - multiply by itself)

when you bring all the measured values to dm (decimeter = 10 centimeters) you'll get the volume in dm3 (cubic decimeters , equals liters)

The length does not affect the bouyancy.

2" PVC wieghs 0.68 #/lin. ft. Water weighs 62.4 #/ft^3 (0.0361#/in^3)

The OD of 2" PVC is 2.375" (area 1.41 in^2)

Displacement of a 30" section is 42.3 in^3 or 42.3 X 0.0361 = 1.53#

The weight of 30 inches at 0.68#/ft = 1.70 #

2-inch PVC is negatively bouyant.

It all depends on what you store inside the pipe. Is it sealed closed or open to allow water entry?

My usual quick number is 13. Some people don't like it, but it works for me!

Thank you all, but you are losing me with the formulas. I am too mentally challenged at this point in my life to think that clearly.

I was hoping for a simple answer in ounces or pounds of bouyancy.

Each 'tube' will have to be matched in equal bouyancy to a set number of floats which have 9 oz. of bouyancy in saltwater per float.

I just need to know HOW MANY FLOATS to substitute for EACH size of tube??

Thank you all again for any help.

How about some contextual information? Please describe the application for these tubes; what is it that these buoyancy tubes are expected to do? Why couldn't one use, oh, say polystyrene swimming pool floats instead? Please explain.

It mounts on an apparatus that is used to hold a net open on the surface of the water.

Soft polystyrene would not hold up to the rigors of daily use. The PVC tubes have worked extremely well. Now, I have one customer who does not want the pvc tubes as he feels they may crack if dropped or banged up onboard. he would like me to use a rod, with a set amount of 3"x3" , 9 oz. bouyant floats threaded onto it, instead.

I just need to know what bouyancy these tubes have. I have never measured them as they are put in tandem on each device, encased in a heavy duty HDPE net sack and strapped down. These sizes work excellent on each different sized device....but for this case i need to know how many 9 oz. floats to substitute.

My previous post forgot the small matter of pi.

For these purposes the difference between seawater and fresh is not significant (1.027)

The net lift (weight of water displaced less the weight of the pipe) is:

30" 3.1 lbs

36" 3.8 Lbs

42" 4.3 Lbs.

This is for sched. 40 - OD = 2.375 " wt per foot 0.68 Lbs

Perfect. Simple....and exactly what I needed.

rate 1 for GA

Thank you.

Using outside measurements you find the volume of your cylinder: Volume = pi x r2 x Length. Your buoyancy will be about equal to the weight of that volume of water.