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The XYXA chemical storage tank breather manhole is a multi‑function safety device installed on the roof of fixed roof tanks, integrating manhole access with breather valve functions, combining personnel entry, overpressure relief, vacuum intake, flame arrestor, and explosion‑proof protection. When the tank pressure exceeds the set value, the pressure disc automatically opens to release excess gas; when vacuum occurs, the vacuum disc opens to admit air or blanketing gas; the built‑in flame arrestor effectively blocks external flame ingress; the manhole cover can be opened for personnel to enter the tank for cleaning or maintenance. Its core purpose is to provide a single safe interface for tanks in chemical, petroleum, storage & transportation, pharmaceutical and other industries that combines safe access, automatic pressure balancing, and fire/explosion protection, especially suitable for applications requiring reduced roof openings and enhanced safety.

XYXA breathing manhole product diagram
Features:
1. Multi‑function integration: Combines manhole cover and breather valve into one unit, reducing roof openings and leakage points, simplifying installation and maintenance.
2. Set‑pressure breathing with automatic regulation: Independent pressure and vacuum discs automatically relieve overpressure and admit air under vacuum; pressure settings adjustable as required.
3. Built‑in flame arrestor: Stainless steel corrugated plate flame arrestor core effectively blocks external flame propagation, meeting petrochemical tank fire and explosion codes.
4. Personnel access function: The manhole cover provides a standard‑size opening (e.g., DN500, DN600) for personnel wearing respirators to enter the tank for maintenance.
5. Large flow capacity with low pressure drop: Optimized flow path ensures low breathing resistance for both venting and gas intake during rapid filling or discharging.
6. All‑weather protection structure: Rain and dust cover with internal drainage prevents water accumulation, suitable for harsh outdoor environments.
7. Corrosion‑resistant materials: Housing and internals available in aluminum alloy, carbon steel, or stainless steel; disc and flame arrestor core in stainless steel for various corrosive media.
8. Reliable sealing and easy maintenance: Flat or tapered hard seal provides zero leakage when closed; removable flame arrestor core for cleaning; simple disc assembly disassembly.


Structural diagram of XYXA breathing manhole
Drawing of Parts
| 代号 (Code) | 材料牌号 | 代号 (Code) | 材料等级(Material Grade) | 相应牌号 (Corresponding Grade) | |
| Ⅰ | 0Cr19Ni9 | 20 | 0Cr18Ni10Ti | 20 | 304 |
| Ⅱ | 0Cr19Ni11 | V | 0Cr18Ni10Ti | 304L | 321 |
| Ⅴ | 0Cr19Ni11 | Ⅵ | 0Cr17Ni14Mo2 | 316 | 316L |
Performance Specification Table
| 正压Class A Positive Pressure | +1961.2Pa(+200毫米汞柱)+1961.2 Pa (+200 mmHg) |
| 负压Negative Pressure | -392.2.2Pa(-40毫米汞柱)-392.2.2 Pa (-40 mmHg) |




Outline drawing of XYXA breathing manhole
Outline dimension table
Standard No.:SHJ510-58 0.6MPa (Pg 6Kg/cm²)
| 公称通径 DN Nominal Diameter DN | 法兰外径 D Flange Outer Diameter D | 螺栓孔中心圆直径 D1 Bolt Hole Center Circle Diameter D1 | 法兰密封面直径 D2 Flange Sealing Surface Diameter D2 | 法兰厚度 b Flange Thickness b | 螺栓数量 - 孔径 N-d No. of Bolts - Hole Diameter N-d | 密封面高度 f Sealing Surface Height f |
| 500 | 640 | 600 | 570 | 30 | 16Φ23 | 4 |
| 600 | 755 | 705 | 670 | 30 | 20Φ25 | 4 |
Standard No.:SHJ510-58 1.0MPa (Pg 10Kg/cm²)
| 公称通径 DN Nominal Diameter DN | 法兰外径 D Flange Outer Diameter D | 螺栓孔中心圆直径 D1 Bolt Hole Center Circle Diameter D1 | 法兰密封面直径 D2 Flange Sealing Surface Diameter D2 | 法兰厚度 b Flange Thickness b | 螺栓数量 - 孔径 N·d No. of Bolts - Hole Diameter N·d | 密封面高度 f Sealing Surface Height f |
| 500 | 670 | 620 | 585 | 32 | 20Φ25 | 4 |
| 600 | 780 | 725 | 685 | 36 | 20Φ30 | 5 |
Standard No.:SHJ406-89 PN2.0MPa (ANSI 150Lb)
| 公称通径 DN Nominal Diameter DN | 法兰外径 D Flange Outer Diameter D | 螺栓孔中心圆直径 D1 Bolt Hole Center Circle Diameter D1 | 法兰密封面直径 D2 Flange Sealing Surface Diameter D2 | 法兰厚度 b Flange Thickness b | 榫槽深度 V Tongue &Groove Depth V | 螺栓数量 - 孔径 N-d No. of Bolts - Hole Diameter N-d | 密封面高度 f Sealing Surface Height f |
| 500 | 699 | 635 | 584 | 43 | 73 | 20Φ33 | 1.6 |
| 600 | 813 | 749.5 | 692 | 43 | 33 | 20Φ36 | 1.6 |

Model:
ZGB-III-16/ZGB-III-25 ZGB-III-16C/ZGB-III-25C/ZGB-III-16P/ZGB-III-25PSpecification:
DN15-DN200Pressure:
1.6MPa-2.5MPaMaterial:
cast iron, cast steel, stainless steel
Model:
HX2-16/HX2-25/HX2-16P/HX2-25P/HXF2-16/HXF2-25/HXF2-16P/HXF2-25PSpecification:
DN40-DN400Pressure:
1.6Mpa-2.5MpaMaterial:
cast steel,aluminium alloy, stainless steel
Model:
HGS07-203-6C/HGS07-203-10C/HGS07-203-25C/HGS07-203-6P/HGS07-203-10P/HGS07-203-25PSpecification:
DN50-DN150Pressure:
1.6MpaMaterial:
cast iron, cast steel, stainless steel