Type 318V - Tank sight glass for vacuum | ACI Industriearmaturen GmbH

Circular Sight Glass Fittings Type 318V - PN 2.5 

for vacuum applications

Tank Sight Glass Type 318V

Our round tank sight glasses type 318V are welded on or in vessel walls to allow observation or illumination of the inside of the vessel. ACI tank sight glasses type 318V are designed based on DIN 28120 for vacuum applications up to -0.9 bar(g) and for an operating pressure of 2.5 bar(g). A sight glass made of chemically highly resistant borosilicate glass DIN 7080 is clamped between two high-quality stainless steel flanges and proven quality seals. The vacuum is sealed on the media side by means of sealing rings.


Compared to the design specified in DIN 28120, our Type 318V is significantly thinner and lighter. With the gaskets specially designed for vacuum applications, the Type 318V is a cost-efficient alternative for low operating pressures and therefore perfectly fills the application range between our type 317 for pressureless operation and the more solid type 320 variant.

Despite the lower requirements, compared to DIN 28120, our tank sight glasses of type 318V are made of the same high-quality stainless steel 1.4571 (316Ti) that our customers have appreciated for years. The glass material used is borosilicate glass 3.3 to DIN 7080, which has proven itself in the industry. The valve is sealed with sealing rings according to DIN 11851 from a wide range of materials such as PTFE (Teflon®), NBR, EPDM or silicone, which are adapted to vacuum applications.

Should the process conditions pose a problem even for the highly resistant borosilicate glass, an FEP or mica protective screen specially adapted to the fitting offers additional protection against steam and aggressive chemicals, such as alkalis up to a pH value of 14.

Like other of our sightglass fittings, the type 318V can be equipped with wiper type SWI, spray devices or lights on request.

More technical details about our tank sight glass type 318V can be found in the data sheet or in the product video.

Technical data

Flange material:

  • Base flange: 1.4571 (factory standard)
  • Cover flange: 1.4571 (factory standard)
  • Other materials on request


  • similar to DIN 28120 but as lighweight design for vacuum applications


  • up to 200 °C¹ with borosilicate glass according to DIN 708

Sight glass:

  • Borosilcate glass untempered 

Nominal size:

  • DN 50 up to DN 300


  • Wiper SWI with PTFE or silicone wiper blade
  • LED lights for EX- and Non-EX-areas
  • Spray device SVI
  • FEP protective screen (for higher pH-values)
  • special desgins are possible 


  • PTFE, FKM, NBR, Silikon, EPDM
  • or according to customer requirements

Nominal pressure:

  • PN 2,5
  • Vacuum up to -0,9 bar(g)²


  • A4-70

¹limited by gasket

²depending on environmental variables

DN 50 80 100 125 150 200 300
Da [mm] 150 175 200 220 250 300 400
Di [mm] 80 100 125 150 175 225 305
h1 [mm] 12 14 14 16 16 16 20
h2 [mm] 24 24 24 24 24 24 24
kg 3,4 4,8 5,7 6,6 8,3 10,8 20,8

Request an offer
+49 (0) 2461 91634 00
Offer request Offer
Data sheet download Data sheet
Drawing Drawing
STP-Data STP-Data
Productvideo Productvideo
Type 318V - Tank sight glass for vacuum