You need a Buchholz relay of type 22 (BB 25) with 1 cable gland M20x1,5. The damper should respond at a flow rate of 1.00 m/s. The upper switching system should be equipped with one switching element (magnet contact tube) and the lower with two switching elements (magnet contact tubes). The upper switching element should be designed as one normally closed contact, and the lower as two normally closed contacts. The device should be delivered in colour RAL 7033, IP code 66, damper held in response position and with premounted Harting connector 59A. Based on the above data the relay ordered has the following

type code: 22-5.23.25.39.44.59A.-0224

Explanation:
22 = Double-float Buchholz relay Type 22 (BB 25)
  5 = M20x1,5: 1 Harting connector and 1 dummy plug
23 = Damper held in response position
25 = Lower switching system eqipped with two magnet contact tubes
39 = IP code 66
44 = Casing colour RAL 7033 (cement-grey)
59 A = With premounted Harting connector 59 A (See Section 7 in the operating instructions)
02 = Damper setting: 1.00 m/s +/- 15 %
  2 = Contact setting of upper switching system: 1 normally-closed contact
  4 = Contact setting of lower switching system: 2 normally-closed contacts