Penn P78 Series Installation Manual

P78 Series Controls for Dual Pressure and Hazardous
Location Applications
Installation Guide
P78XLCW
Applications
P78 Series Controls for Dual Pressure and Hazardous Location Applications provide combined high and low
pressure control using a low energy signal from inside an explosive zone on commercial refrigeration and
air-conditioning applications. The controls have special dry circuit switches with gold-plated contacts for improved
contact characteristics that are required in circuits with low voltage and low current
IMPORTANT: Use this P78 Series Control only as an operating control. Where failure or malfunction of the
control could lead to personal injury or property damage to the controlled equipment or other property, additional
precautions must be designed into the control system. Incorporate and maintain other devices, such as
supervisory or alarm systems or safety or limit controls, intended to warn of or protect against failure or
malfunction of the control.
IMPORTANT : Utiliser ce P78 Series Control uniquement en tant que dispositif de contrôle de fonctionnement.
Lorsqu'une défaillance ou un dysfonctionnement du contrôle risque de provoquer des blessures ou
d'endommager l'équipement contrôlé ou un autre équipement, la conception du système de contrôle doit
intégrer des dispositifs de protection supplémentaires. Veiller dans ce cas à intégrer de façon permanente
d'autres dispositifs, tels que des systèmes de supervision ou d'alarme, ou des dispositifs de sécurité ou de
limitation, ayant une fonction d'avertissement ou de protection en cas de défaillance ou de dysfonctionnement
du contrôle.
These controls are available in several pressure ranges and are compatible with propane refrigerants. They are
designed to operate in
• Group II, Zone 2 environments, as defined in the ATEX Directive and UKEx regulations.
• Class I, Division 2, Group D environments, as defined in NFPA 70 and CSA C22.2.
They are equipped with fail-safe double bellows on the high side, and two 6 mm outer diameter copper tubes for
connecting to the refrigerant lines. Two adjustment lock plates are included with these models.
IP54 (Type 1 NEMA) enclosures are standard on these models.
P78 control models allow users to install alarm devices or other control circuits (see Figure 4).
Table 1 lists the standard models and features of P78 controls for dual pressure and hazardous location
applications. These standard models are available through most authorized Johnson Controls®/Penn distributors.
Table 1: Standard P78 Dual Pressure Controls for non-corrosive refrigerants
Model number Pack type
P78XLCW-18000C Individual pack
Low pressure side
Range,
barg (psig)
-0.5 to 7
(-7.25 to 102)
P78 Series Controls for Dual Pressure and Hazardous Location
Applications Installation Guide
Part No. 24-7664-3248, Rev. C
High pressure side
Differential, Range,
barg (psig)
bar (psi)
0.6 to 3 3 to 30
(9 to 44) (44 to 435)
1
Issued June 2023
.
Maximum
bellows
Differential,
pressure,
bar (psi)
barg (psig)
3 fixed LP: 22 (319)
(44)
HP: 33 (479)