Low air pressure monitoring is required for any dry system which is located at a facility which requires "Supervised" automatic sprinkler systems as outlined in the Life Safety Code AND they are also required for any dry system which protects a system with sprinkler piping in an area below 32F (Refrigerated Area Systems).
NFPA 13 (2002 Edition):
D.5 Supervision.
D.5.1 Supervisory Signals. Where supervised, automatic sprinkler systems are required by another section of NFPA 101, supervisory attachments shall be installed and monitored for integrity in accordance with NFPA 72, National Fire Alarm Code, and a distinctive supervisory signal shall be provided to indicate a condition that would impair the satisfactory operation of the sprinkler system. This shall include, but not be limited to, monitoring of control valves, fire pump power supplies and running conditions, water tank levels and temperatures, pressure of tanks, and air pressure on dry-pipe valves. Supervisory signals shall sound and shall be displayed either at a location within the protected building that is constantly attended by qualified personnel or at an approved, remotely located receiving facility.
Also from NFPA 13 (2002 Edition):
7.8.2* Spaces Maintained at Temperatures Below 32°F (0°C).
7.8.2.1 General.
7.8.2.2 Low Air Pressure Alarm.
7.8.2.2.1 Unless the requirements of 7.8.2.2.2 are met, a low air pressure alarm to a constantly attended location shall be installed.
7.8.2.2.2 Systems equipped with local low pressure alarms and an automatic air maintenance device shall not be required to alarm to a constantly attended location.
Life Safety Code (2003 Edition)
9.7.2.1* Supervisory Signals. Where supervised automatic sprinkler systems are required by another section of this Code, supervisory attachments shall be installed and monitored for integrity in accordance with NFPA 72, National Fire Alarm Code, and a distinctive supervisory signal shall be provided to indicate a condition that would impair the satisfactory operation of the sprinkler system. System components and parameters that shall be monitored shall include, but shall not be limited to, control valves, fire pump power supplies and running conditions, water tank levels and temperatures, tank pressure, and air pressure on dry-pipe valves. Supervisory signals shall sound and shall be displayed either at a location within the protected building that is constantly attended by qualified personnel or at an approved, remotely located receiving facility.
The life safety code requires "Supervised" automatic sprinkler systems for many many occupancies; in summary, it really depends on the given occupancy where the dry system is located.
I hope this helps!
