WATER TANK PLUMBING

Have a certified technician install all parts to prevent product damage and personal injury.


All water tanks we carry must be vented, they are not pressurized tanks allow air to move in and out when filling and emptying the tank.

Do NOT fill the tank directly from a pressurized line (garden hose), this is not a safe option and will explode the tank. We recommend using a fill dish to allow for gravity feeding of the tank, please review our plumbing example for more information.


What fittings will I need?

This will depend on how you are setting-up your tank and will vary by application. Please view our Plumbing Category for information on loose fittings we carry.


At this time Class A Customs only installs the following fittings into our Fresh / Gray tanks

1/2" NPT Female

1 1/2" NPT Female

1 1/4" Outer Diameter x 2: Long Smooth Pipe (Boss Fitting)


It is recommended to use plastic male fittings with plastic female fittings to avoid damaging the threads, metal thread fittings can crush the plastic threads.







You can also have fittings moved in tanks to help make plumbing easier. WATER TANK FORM


National Pipe Threads (NPT)

Pipe sizes do refer to physical dimensions, but the plumbing industry standard for the sizes of pipe is not always as straight-forward as measuring the pipe. Measuring the pipe will oftentimes mislead you into choosing the wrong pipe, so do take care. The "pipe thread size" as shown in column 3 of the table below is measured and based on the inside of the pipe. But, to actually determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI). The 3/4" NPT pipe thread has 14 threads per inch. Both the TPI (threads per inch) and OD (outside diameter) of the thread are required for positive identification of thread size because several sizes have the same TPI.


Male threads:Measure the outside diameter of the large portion of the thread at "A"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size.

Female Threads:Measure top diameter of thread at "B"; Find figure nearest this dimension in column 1 or 2 of chart. The dimension in column 3 will be your nominal pipe thread size.



Col 1

(Dimension A)

Col 2

(Dimension A)

Col 3

(Dimension B)

Col 4

(Dimension C)

Col 5

Col 6

OD

Fraction Inch

(quick reference only)

OD Actual

(inches)

Pipe Thread

Size

Normal engagement

for tight joint

Threads

per Inch

Circumference

(inches)

5/16

0.3125

1/16

0.2611

27

0.9817

13/32

0.405

1/8

0.2639

27

1.272

35/64

0.540

1/4

0.4018

18

1.696

43/64

0.675

3/8

0.4078

18

2.121

27/32

0.840

1/2

0.5337

14

2.639

1-3/64

1.050

3/4

0.5457

14

3.299

1-5/16

1.315

1

0.6828

11-1/2

4.131

1-21/32

1.660

1-1/4

0.7068

11-1/2

5.215

1-29/32

1.900

1-1/2

0.7235

11-1/2

5.969

2-3/8

2.375

2

0.7565

11-1/2

7.461

2-7/8

2.875

2-1/2

1.1375

8

9.032

3-1/2

3.5

3

1.2000

8

10.995

4

4.0

3-1/2

1.2500

8

12.566

4-1/2

4.5

4

1.3000

8

14.137

5-5/8

5.563

5

1.4063

8

17.476

6-5/8

6.625

6

1.5125

8

20.812

8-5/8

8.625

8

1.7125

8

27.095

10-3/4

10.75

10

1.9250

8

33.771

12-3/4

12.75

12

2.1250

8

40.054


Definition of pipe thread acronyms

NPT

National Pipe Thread (tapered)

FPT

Female Pipe Thread (interchangeable with NPT)

FIP

Female Iron Pipe (interchangeable with NPT)

MPT

Male Pipe Thread (interchangeable with NPT)

MIP

Male Iron Pipe (interchangeable with NPT)

IPS

Iron pipe size (interchangeable with NPT)

PTF

SAE short taper pipe thread

NPTF

National Pipe Thread Fuel (American National taper pipe thread for dryseal pressure-tight joints)

NPSM

National Pipe Straight Mechanical (American National straight pipe thread for mechanical joints)

NPSI

American National straight intermediate pipe thread

GHT

Garden Hose thread

NST

National Standard Thread (Fire Hose thread)

BSPT

British Standard taper pipe thread (metric dimensions)