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For welding in or on
Level indicator for operating pressures up to 35 barg
Non binding • Usually a response within 24 hours
The longitudinal sight glass fitting Type 330 is a rectangular vessel sight glass for welding into or onto vessel walls. It enables reliable visual inspection of the liquid level in closed vessels such as boilers, tanks or silos.
Due to its elongated design, the longitudinal sight glass provides a larger viewing area than round sight glass fittings and is particularly suitable for applications where the fill level needs to be read or monitored directly on the vessel.
The fitting can either be welded into the vessel wall or welded onto the vessel wall.
The longitudinal sight glass Type 330 is manufactured as standard from corrosion-resistant stainless steel 1.4571 and is designed for use on boilers, tanks, silos and closed vessels.
Depending on the version, reflex or transparent sight glass made of borosilicate glass according to DIN 7081 is used for the sight glass plate.
For sealing, different flat gasket materials are available. These include PTFE, NBR, novaphit® MST-XP, KlingerSil® C4400 and other gasket materials for different media, temperature and process requirements.
For applications in poorly illuminated vessels, the use of a reflex sight glass according to DIN 7081 or comparable is recommended. Special prism structures are incorporated into these glasses, which refract and reflect the incoming light – making the liquid level significantly easier to detect.
If the vessel is well illuminated, the medium is very clear or the colour of the medium should also remain visible, a transparent sight glass is the better choice. It enables undistorted viewing and precise optical inspection of the contents.
Mica-protected transparent glass plates support use at high temperatures or under steam exposure up to max. 320 °C. FEP or Halar® coatings protect the borosilicate glass on the media side in applications involving aggressive chemicals or alkalis. Please note that reflex sight glasses cannot be combined with mica discs or coatings; these options are only intended for transparent sight glasses.
In addition, high-temperature versions, virtually dead-space-free versions with stepped glass and application-specific special designs are possible.
Typical applications for the longitudinal sight glass Type 330 include boilers, tanks, silos, vessels and technical plants where the liquid level needs to be reliably checked visually. The fitting is particularly suitable for applications where an elongated viewing area is required directly on the vessel.
| Pressure notes PS 16 | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| BL [mm] | 140 | 170 | 220 | 250 | 300 | 310 | 350 | 370 | 400 | 500 | 600 | 320 | 700 | 740 | 800 | 930 | 1000 |
| SL [mm] | 79 | 124 | 174 | 204 | 264 | 264 | 304 | 324 | 354 | 454 | 564 | 564 | 654 | 694 | 754 | 884 | 954 |
| Concealed view [mm] | 0 | 1x46 | 1x36 | 1x46 | 1x46 | 1x46 | 1x46 | 2x46 | 3x46 | ||||||||
| h1/h2 [mm] | 20 | ||||||||||||||||
| PS max [barg] | 16 | ||||||||||||||||
| TS max [°C ]¹ | 320 | ||||||||||||||||
| Weight [kg] | 2,8 | 3,2 | 4,0 | 4,6 | 5,3 | 5,6 | 6,3 | 6,6 | 7,1 | 9,1 | 10,7 | 11,1 | 12,5 | 13,2 | 14,2 | 16,7 | 18,2 |
1) Depending on the glass material, gasket material and design
| Pressure notes PS 35 | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| BL [mm] | 140 | 170 | 220 | 250 | 300 | 310 | 350 | 370 | 400 | 500 | 600 | 320 | 700 | 740 | 800 | 930 | 1000 |
| SL [mm] | 79 | 124 | 174 | 204 | 264 | 264 | 304 | 324 | 354 | 454 | 564 | 564 | 654 | 694 | 754 | 884 | 954 |
| Concealed view [mm] | 0 | 1x46 | 1x36 | 1x46 | 1x46 | 1x46 | 1x46 | 2x46 | 3x46 | ||||||||
| h1/h2 [mm] | 25 | ||||||||||||||||
| PS max [barg] | 35 | ||||||||||||||||
| TS max [°C ]¹ | 280 | ||||||||||||||||
| Weight [kg] | 3,4 | 4,0 | 5,0 | 5,7 | 6,6 | 6,9 | 7,8 | 8,2 | 8,8 | 11,3 | 13,3 | 13,8 | 15,6 | 16,4 | 17,7 | 20,8 | 22,6 |
1) Depending on the glass material, gasket material and design
The Type 330 longitudinal sight glass is designed for applications on boilers, tanks, silos and closed vessels where the liquid level needs to be reliably checked visually. The fitting is used as a level indicator and can be welded into the vessel wall or welded onto the vessel wall.
The Type 330 is designed for the pressure ratings PS 16 and PS 35. Depending on the design, operating pressures of up to 35 barg are possible. This makes the longitudinal sight glass suitable for applications that require a robust sight glass fitting for level control.
The Type 330 longitudinal sight glass can be either welded into the vessel wall or welded onto the vessel wall. This allows the fitting to be positioned directly on the vessel and used as a sight window to monitor the liquid level.
A reflex sight glass has special prism structures that refract and reflect the incident light. This makes the liquid level easier to detect in poorly lit vessels. A transparent sight glass, by contrast, allows a clear view and is particularly suitable when the medium must remain clearly visible or its color needs to be assessed. You can find a detailed explanation of the differences between reflex glass and transparent glass here.
Reflex sight glasses operate with a special prism structure that makes the liquid level more visible through light refraction. Mica protective discs would be damaged by pressure loading because of the prism structure. Therefore, mica protective discs and coatings are only provided for transparent sight glasses.
Options for Type 330 include, among others, FEP or Halar® coatings, mica protective discs, high-temperature versions, nearly dead-space-free designs and custom constructions. These options serve to adapt the longitudinal sight glass to requirements such as thermal load, chemical media resistance, cleaning or special installation situations.
