Larry Jaques wrote:

On Sun, 15 Jan 2012 16:13:39 -0500, axolotl
wrote:


I brought home a Blackhawk "Porto Power" hydraulic hand pump with a set
of spreading jaws from yesterday's Cabin Fever. I would place the
manufacturing date as perhaps the 40's.
The rehab process brings up some questions:

The pump output port is connected to a 4" length of what appears to be
plain 3/8" iron pipe. This pipe connects to what appears to be a plain
iron union (?), with a reducing bushing for the hose on the other side
of the union. Are plain iron pipe fittings acceptable for high pressure
hydraulic use, or is this a kluge? (For my uses the pipe/union are
coming off.)

This style of pump is sold as a "10 Ton" pump. The piston on the jaws
appears to have an internal diameter of 1.5", so it would appear that I
would have to put 11000+ pounds of pressure on the fluid to get 10 Tons
at the piston. Pressure fittings and hoses for this use do not have that
high of a pressure rating. What am I missing?

Hydraulic pressure in the line is much less than total at the piston.
Area of the piston divided by area of the line is the ratio.
http://www.capetronics.com/images/basics6.gif
Pressure hose we used on autos was usually rated at 3-6kpsi and run at
1.8-3kpsi.

Here ya go. Plug in your known numbers:
http://www.engineersedge.com/fluid_f...ssure_pipe.htm

I can't find burst pressure for black iron pipe or fittings.

The hand pumped porta-power and enerpak hydraulic stuff is generally
considered 10,000 PSI hydraulics. The hand pumped stuff operates at much
higher pressures than most mobile equipment, in part because hand pumped
stuff is non-shock hydraulics that doesn't see the pressure spikes
common to mobile equipment. The safe operating pressures for small dia
*quality* black pipe are going to be more like 1,500 PSI at best.