Weathertight Mushroom Ventilator with Fan Blower | CB/T 295 Type B Welded Deck

Product Specification

Weathertight Mushroom Ventilator with Fan Blower | CB/T 295 Type B Welded Deck Air Vent Head

Product Overview

The CB/T 295 Type B weathertight mushroom ventilator is a welded deck ventilation head used on exposed ship decks for natural ventilation or as the deck terminal of a mechanical ventilation system connected to a fan blower. The mushroom cover is adjusted by a handwheel and screw stem so the opening can be raised, lowered, or closed to control airflow and help maintain weathertight protection when required.

This page is prepared for DN250 to DN1400 Type B mushroom ventilators based on the supplied CB/T 295-2000 data. Public standard information shows that CB/T 295-2000 has been replaced by CB/T 4444-2017, so the required edition should be confirmed by the vessel drawing, shipyard specification, or class requirement. Fan blower capacity, motor power, voltage, airflow, static pressure, noise level, and duct arrangement are not included in the supplied dimension table and should be confirmed separately when the fan unit is included in the order.

Quick Specifications

• Product type: Weathertight mushroom ventilator with fan blower interface → deck air vent head for natural or mechanical ship ventilation systems.
• Standard reference: CB/T 295-2000 Type B → supplied table basis; CB/T 4444-2017 should be checked when the project requires the current Chinese marine mushroom ventilator standard.
• Nominal diameter range: DN250 to DN1400 → selected according to air duct size, ventilation demand, deck opening, and arrangement drawing.
• Installation form: welded Type B arrangement → suitable for deck-mounted ventilation heads where welded installation is specified.
• Operation: outside handwheel / screw-stem operation → cover opening can be adjusted for airflow control and closed when weathertight protection is required.
• Screen arrangement: stainless mesh or specified insect / rodent screen → helps prevent unwanted entry while keeping the air path open.
• Material options: mild steel, stainless steel, bronze, or copper → final material should follow corrosion environment, duct material, and class requirement.
• Weight range from supplied table: 52 to 674 kg, excluding air duct → useful for handling, lifting, packing, and freight planning.

Main Technical Parameters

Selection & Inquiry Guide

Step 1: Confirm the required standard and edition: CB/T 295-2000, CB/T 4444-2017, vessel drawing, or customer-specific standard.

Step 2: Confirm the nominal diameter DN250 to DN1400 according to duct diameter, air volume requirement, deck opening, and available installation space.

Step 3: Confirm whether the ventilator is used for natural ventilation only or connected to a fan blower for supply / exhaust mechanical ventilation.

Step 4: Confirm the operating arrangement: Type B outside handwheel operation, screw-stem direction, cover travel, gasket requirement, and whether a support bracket is needed for high air pipe arrangements.

Step 5: Confirm material and surface treatment: mild steel, stainless steel, bronze, copper, Sa2.5 blasting + epoxy shop primer, galvanizing, polishing, or special coating system.

Step 6: Confirm screen and closing details: stainless mesh, insect / rodent screen, fire screen if required, sealing gasket, drain consideration, and weathertight closing requirement for the deck position.

Step 7: Provide quantity, vessel type, installation location, air duct drawing, fan blower data if included, class certificate requirement, delivery destination, and required delivery time.

Structure

Mushroom hood | Movable weathertight cover | Handwheel | Screw stem | Sealing gasket | Stainless mesh / insect screen | Welded ventilation cylinder | Air duct / fan blower interface | Deck welding area | Shop primer or specified surface finish

Ventilation, Weathertightness & Engineering Advantages

• Type B outside operation allows the mushroom cover to be opened, adjusted, or closed from the top side, which is suitable when the deck arrangement and ventilation route require external access.
• The mushroom hood helps shield the air opening from direct rain entry while still allowing ventilation through the duct opening when the cover is raised.
• The welded installation arrangement provides a fixed deck connection; welding quality, deck penetration detail, and coating repair after installation should be confirmed by the shipyard.
• The handwheel and screw stem should move smoothly, and the movable parts should be lubricated and maintained so that the cover can be operated reliably during service.
• Stainless mesh or project-specified screening can help prevent insects, rodents, and foreign matter from entering the ventilation duct.
• When used with a fan blower, the ventilator should be checked together with fan airflow, static pressure, duct resistance, noise requirement, and backflow / weather closing arrangement.
• For ventilators installed in exposed deck positions, the weathertight closing arrangement should be confirmed against the vessel load line, class, and flag requirement.
• Large DN sizes should be reviewed for lifting, deck access, air pipe height, bracket support, coating maintenance, and packing before production.

Custom Attributes

• Standard: CB/T 295-2000 Type B → use when the vessel specification still calls for the older CB/T mushroom ventilator table.
• Current Standard Check: CB/T 4444-2017 → public standard information shows it replaces CB/T 295-2000, so the required edition should be confirmed.
• Nominal Diameter: DN250 to DN1400 → select according to duct size, airflow requirement, and deck arrangement.
• Operation: Outside handwheel and screw stem → cover opening can be adjusted to control ventilation and closed when required.
• Fan Blower Interface: To be confirmed → supplied table covers the ventilator head; fan capacity, motor, voltage, airflow, and pressure are separate order data.
• Material: Mild steel / stainless steel / bronze / copper → final material and corrosion protection should match vessel service environment.
• Screen: Stainless mesh or specified screen → used for insect, rodent, and foreign matter protection according to project requirement.
• Surface Treatment: Sa2.5 blasting + epoxy shop primer / galvanized / polished / customized → final coating follows shipyard paint specification.
• Certificate Requirement: Available according to order scope → class certificate, maker certificate, material certificate, and inspection report should be confirmed before quotation.

How It Works

Air duct or fan blower is connected below the deck ventilator → Handwheel adjusts the mushroom cover height → Air passes through the raised cover opening and screen → The cover can be lowered for weathertight closing when required → Inspection, lubrication, and coating maintenance keep the ventilator serviceable

Applications

Open deck ventilation | Accommodation ventilation | Galley ventilation | Machinery space supply or exhaust duct | Store room ventilation | Fan blower deck outlet | Natural and mechanical ventilation systems | Newbuilding and replacement projects

Certifications & Advantages

Certificates can be arranged according to project requirement, inspection scope, material traceability, weathertight closing requirement, and class society approval procedure.

Certification: CCS, NK, BV, ABS, DNV, LR, KR, IRS, RS, RINA, CRS, Makers Test Certificate.

Drawing & Photos

FAQ

Q1: Does the product include the fan blower?

A1: The supplied technical table defines the CB/T Type B mushroom ventilator head. If the order includes a fan blower, the airflow, static pressure, motor power, voltage, frequency, protection grade, noise limit, duct connection, and control requirement should be confirmed separately.

Q2: What is the difference between Type B and other mushroom ventilator types?

A2: Type B is generally a welded arrangement with outside opening and closing operation. If the vessel requires inside operation, bolted installation, fixed ventilation, or another operating arrangement, the type should be confirmed from the vessel drawing or standard table.

Q3: Should CB/T 295-2000 or CB/T 4444-2017 be used?

A3: The supplied data is based on CB/T 295-2000. Public standard information shows that CB/T 4444-2017 replaced CB/T 295-2000. The final order should follow the shipyard specification, owner requirement, class approval, or replacement drawing.