I am sorry to hear that the instrument on the Mississippi Queen
was "starving for Steam"  As I think was mentioned in a previous
posting, the MQ is normally tuned at a nominal pressure not to exceed
15 PSIG.  A pressure of 9 PSIG is too low as the writer has stated.

Who ever it was who informed the gentleman that the pressure was
reduced so as not disturb passengers, was probably misinformed.  Based
on my knowledge of the situation, I would assume that there is a
maintenance problem, rather than a change in philosophy.

Last time we tuned the MQ, we had some problems with pressure
regulation, initially.  I thought we had corrected the problem, but
perhaps it persists.

Steam is supplied off of the main header (steam is superheated at this
point for the benefit of the two steam turbines that generate the
normal electrical power) to a single stage reducing station.  After
reduction, the steam at a nominal pressure of 50 PSIG (still
superheated) is trapped and is sent up several decks to the pressure
regulator for the calliope.  This regulator at the calliope is a
6" Fisher with a separate pilot.  The pilot senses the main manifold
pressure (the point of feedback is critical) and compares that to the
"set" spring pressure across a stainless steel diaphragm.  A signal is
then generated and sent to the main valve such that if the pressure in
the manifold is below the setpoint, an applied pressure causes the
valve to open.  As the set pressure is approached, the control pressure
to the main valve is decreased and the valve throttles down.

The regulators have stainless steel diaphragms that must flex
continuously.  The diaphragms are made up in layers.  After a couple
of years the steel begins to fatigue.  A first this causes the
pressure to drift (this may be the condition we are experiencing now).
Eventually the regulator with such a problem will fail entirely.  It
has been about three years since we have rebuilt the calliope
regulator. This is not to say that the regulator may have been rebuilt
more recently by engineering or that someone with a "monkey wrench"
did not play with the regulator setting.

Regardless, I will follow up on this situation.  If there are no
problems requiring our services, I will not see the boats in person
until it is time to make layup preparations.

Sorry, but I am about to time out.

Don Elbers

 [ Don,  Its good to hear from you.  Thanks for writing.   -- Jody