Pressure required for domestic applications

[vinhermes]

Dear all,

In order to size a freshwater pressure set for a ship, I am looking for typical figures for the required residual pressure at a water tap,shower, etc. I could not find this on suppliers' datasheets. Client's specification states that 3 bar shall be available for the user (that I translate as the residual pressure required). This seems high for me. Is this a typical figure? I'd like to know where exactly the pumps (2x100% configuration) will be operating.

Thanks by advance, Vincent Hermes

 

[bimr]

The normal working pressure should be approximately 60 to 80 psi (410 - 550 kPa) in water systems. Note that you do not address the number of deck levels in your ship. If you have a tall ship, you will need to address the change in pressure with different deck levels.

"7.3.1 Pressures
The maximum variation between high and low levels in storage structures providing pressure to a distribution system should not exceed 30 feet. The minimum working pressure in the distribution system should be 35 psi (240 kPa) and the normal working pressure should be approximately 60 to 80 psi (410 - 550 kPa). When static pressures exceed 100 psi (690 kPa), pressure reducing devices shall be provided on mains or as part of the meter setting on individual service lines in the distribution system."

http://10statesstandards.com/waterrev2012.pdf

 

[vinhermes]

Dear Bimr,

Thank you for your reply.

Static head and friction losses are taken into account separately. I understand from your document that around 500kPa (5 bar) available right before the tap/shower is standard practice? I would have thought much less than this. I am getting it right?

Thank you for this, Vincent

 

[bimr]

Correct, that is the customary practice in water systems.

 

[vinhermes]

Brillant, thank you.

 

[BRIS]

Most domestic appliances are rated for about 7 bar or so. 5 bar will give you a high pressure shower. However for water conservation and long term reliability 3 bar is good (Domestic PRVs are typically pre set at 3 bar), 0.7 bar is adequate.

 

[vinhermes]

Thanks Bris. I might target a 2 bar at the tap to be safe for other projects but stick with the 3 bars required for this one. Cheers.