QIYUE FAN · FAN-TO-DUCT INTERFACES

Fan Flexible Connector RFQ: Close the Interface Gaps Before Ordering

A quotation that says “flexible connection included” can still leave an installation team missing a mating flange, attachment hardware or an approved material. Treat each inlet and outlet connection as a separate interface, with its own drawing, duty and supply boundary.

Buyer takeaway: identify what connects to what, under which conditions, and who supplies every part. Agree the connector and accessory scope in the quotation.

One interface, three separate approvals

Conceptual review map only. It does not show an assembled joint, support design, installation gap or approved dimensions.

1. Freeze the geometry before comparing prices

Use one marked drawing for both mating sides. Ask the supplier to return a connection detail identifying the joint type, dimensions and attachment method. Do not substitute a catalog photograph for a checked interface.

• Identify inlet or outlet, equipment tag and drawing revision.
• Record round or rectangular geometry and the applicable dimensions.
• For a bolted joint, request the mating flange and hole-pattern details. For a sleeve connection, request the approved end and attachment details.
• Ask the responsible designer to specify the installed span and permitted movement or offset, if any. Do not invent a universal gap.

Why separate the parts? The Greenheck QEI/QEI-M/QEID manual, Duct Connections illustrates different slip-fit and flanged arrangements and separately identifies sleeve and hardware scope. Use the selected equipment’s connection drawing and bill of materials for your order.

2. Request suitability for the actual duty

The Carlisle HVAC flexible-connector technical guidance identifies pressure, temperature, environment, airstream constituents and span as selection inputs. It also warns that excessive fabric droop or folding can affect airflow. Use the selected product’s instructions, not generic fabric ratings or a visual guess.

Where the project has fire, hazardous-area or other special requirements, name them in the RFQ and request product-specific evidence from the responsible party. Do not assume a general-purpose flexible connector meets those requirements.

3. Close the supply boundary line by line

Use included / optional / excluded / by others / pending for each item. “Pending” is preferable to silently assuming it is in the fan price.

Have the equipment and system designers confirm the joint’s function, alignment, load support and any expansion-joint requirements. A vibration complaint still needs its own diagnosis; see the fan vibration review.

Copy one record for each connection

Project / fan tag:
Interface: inlet / outlet / other:
Fan-side drawing and revision:
Duct-side drawing and revision:
Joint type and mating dimensions:
Installed span / movement requirement and design owner:
Pressure conditions, units and reference:
Temperature range and intermittent exposure:
Medium, constituents and environmental exposure:
Connector product / material evidence:
Parts included / optional / excluded / by others:
Installation and support-design responsibility:
Open mismatch, owner and approval reference:

Use this record alongside the general arrangement drawing review and quotation comparison guide. Do not release an unresolved interface on the assumption that the site team can make it fit.