The short answer to your question is: No, there is no published ” pressure rating ” for the infrared (IR) window lens. There actually is no specific Standard existing to begin with requiring specific pressure withstand testing or assigned ratings for IR windows. However, IRISS products and lenses are tested against a minimum challenge of 950°Celsius and 25 PSI. In the case of IRISS only, this information does exist and is derived from the stunning results of much more severe testing parameters which our full product lines are subjected to–and this aspect is uniquely so for IRISS alone as our products are the most tested and certified in this industry and product category.

Additionally, the reinforced polymer optic lens design of our IR windows (part of our Electrical Maintenance Safety Device family) are the only IR window lenses on the market actually subjected to and pass the required IEEE Load & Impact testing for ‘Viewing Panes’.  One essence of this testing is the 2lb steel ball drop onto the center of the IR window lens from a specified height.

IEEE C37 20.2.a.3.6: Impact and Load: Viewing panes mounted in medium and high voltage equipment (600 volts to 38kv metal clad and 72kv station type gear) are required to withstand impact and load per IEEE C37.20.2 a.3.6. The standard specifically states that the viewing pane must withstand the impact and load from both sides (inside/outside) and the viewing pane must not “crack, shatter or dislodge.”

IRISS products are directly arc-fault tested by many of the switchgear OEM’s on assorted electrical gear, both arc rated and non-arc rated. They all consider their test formats, protocols, and resulting data to be very guarded intellectual property and they do not provide ‘Test Certificates’ upon completion of testing — it’s either a pass or fail. IRISS has never failed such a test and we consistently exceed the Standards Requirements set forth as well by the various Standards Bodies globally — IEEE, UL, cUL, CSA, LLoyds, ABS, DNV, IP65/NEMA 4, etc. IRISS’ most recent OEM testing was performed by ABB less than 1 year ago — the fault energy level tested to was 63kA-15kV-60Hz-30 Cycles, and we passed easily.


The typical temperature seen during this type of test is approximately 950°Celsius and the pressure peaks at approximately 25 PSI (depending on the design, could go higher). This is the Temperature and Pressure level resulting from a 63kA, 15kV, 30 cycles arc-fault test in arc resistant switchgear. Further, IRISS reinforced polymer IR optics easily withstand 30 PSI in sealed chamber pressure testing.

The pressure levels in the ISO bus fed pressurized Terminal Boxes in your application will never see any pressures even approaching these levels. Additionally, IRISS actually produces curved IR Inspection and Service Access Panels for mounting specifically onto pressurized and non-pressurized ISO phase bus systems alike.

It’s both relevant and vital to look at the mechanical test requirements for IR windows in the same way as for simply visual viewing windows fitted in switchgear. IRISS is the only manufacturer in this product category that tests its entire line to these much higher IEEE, and other, withstand requirements. As such, the impact, load, flammability and environmental test requirements take on a new meaning — this is why IRISS is the most recognized, certified, and universally approved IR window line globally.