Tejido doble= double layer
Conexion de lona= canvas connection

Mechanical Ventilation System Buyers and Buy Leads - Chennai ...
https://trade.indiamart.com/details.mp?offer=14057600375
Suitable motor for 415 + 10% volts, 50 cycles AC supply with Fan section with ... Heavy duct flexible **double layer canvas connection** needs to be provided at ...

double layer canvas connection needs to be provided at ...
1315977722IITM_HVAC_TD00 | Liquidation | Specification (Technical ...
https://www.scribd.com/document/146925804/1315977722IITM-HVA...
The HVAC tender for this job is High side and low side Air Conditioning and ...... Section 21.4.4.2 Heavy duct flexible **double layer canvas connection** shall be ...

Canvas Connector
Also known as a flex connection, the canvas connector is a strip of metal followed by a strip of canvas material followed by another strip of metal. Utilized to isolate vibration and thus noise from the unit to the ductwork.
http://www.smcduct.com/hvac-industry-dictionary-terms/

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Note added at 5 days (2017-07-22 18:48:18 GMT) Post-grading
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Glad to be able to help.