
APL-4**N Series Limit Switch Box 
 
Installation, Operation & Maintenance Manual
Doc No. : HumG-APL4-21 Rev.1      Page  3 / 12    Valve Automation Leader,  HKC 
1. General  
1.1. HKC APL-4 series limit switch boxes are designed to provide accurate and reliable valve position signalling 
and indicating of most valves or actuators manufactured.  
1.2. APL-4  limit  switch  boxes  consist of  a  visual  position  indicator,  quick-set  cam  ass’y,  terminal  strip,  switch 
ass’y and easy mounting bracket. Quick-set cam allows for a quick and simple hand operation in the setting 
of switches. 
 
2. Ordering Information 
APL -    4  1  0  N  
  ①       ②       ③ 
① Enclosure type of explosion proof is based on IECEx, [CNEX ITRI, --- 21 r1]   :  
             [ Ex db IIB T6 Gb ---- 18 r0] 
Enclosure type of explosion proof is based on ATEX :  
             [ II 2 G Ex db IIB T6 Gb --- 18 r0] 
Enclosure type of explosion proof is based on KCs  :  
              Ex d IIB T6 Gb 
Enclosure type of explosion proof is based on CSA  :  
              Cl I, Div 1, Gr C & D T6 
              Cl I, Zone 1, AEx d IIB T6 
              Ex d IIB T6  
              [NEMA 4X/6, IP 66/67/68 --- 17r0] 
[Enclosure type of explosion proof is based on EAC  :  
              1Ex d IIB T6 Gb X 
              0Ex ia IIC T6 Ga X (APL-420, APL-422 only) 
              Ex tb IIIC T85℃ Db ------------------------------------ 21 r1] 
② Switch type 
Mechanical switch 
[10  :  2-SPDT (Zippy VA2-16) 
11  :  3-SPDT (Zippy VA2-16) 
12  :  4-SPDT (Zippy VA2-16) 
13  :  2-SPST (Zippy VA2-16) 
14  :  2-DPDT (Omron : DZ-10GW-1B) 
15  :  2-SPDT + Potentiometer (Zippy VA2-16) 
16  :  2-SPDT + Signal Unit(4~20mA) (Zippy VA2-16) ---18 r0] 
Proximity switch 
20  :  Proximity sensor (P&F : NJ2-V3-N) 
21  :  Proximity sensor (Autonics : PS17-5DNU) (Except CSA) 
22  :  Proximity sensor (P&F : NJ4-12GM-N) 
23  :  Proximity sensor (P&F : NBB2-V3) 
25  :  Proximity sensor  + Potentiometer (P&F : NJ2-V3-N) 
26  :  Proximity sensor  + Signal Unit(4~20mA) (P&F : NJ2-V3-N) 
[Reed switch 
30A :  Reed sensor (MS-B 301) for general purpose 
30B :  Reed sensor (MK21 model 85, 250V 1A max) for CSA certified use 
31 :  Reed sensor (MK21 model 66, 180V 0.5A max) for CSA certified use 
32 :  Reed sensor (MK21 model 90, 175V 0.52A max) for CSA certified use –17r0] 
③ Enclosure material 
N  :  Aluminium 
 
3. Standard specification 
Model      APL-4**N  
Enclosure Rating    Please refer to “2. Ordering Information, ① Enclosure type” 
Enclosure       High grade aluminium alloy 
Ambient Temperature    [APL-41* : -40°C ≤ Ta ≤ +60 °C  
        APL-414, APL-42*, APL-43* : -20°C ≤ Ta ≤ +60 °C ---18 r0] 
        [-60°C ≤ Ta ≤ +60 °C @ only EAC --- 21 r1] 
Cable Entries      Standard : Two NPT 3/4”, or M25 for Ex type