QC/T 771-2017Specifications for diesel fuel fine filter assemblies with paper elements for automotive diesel engines (English PDF)

3.1 Diesel-fuel fine filter

The last level of diesel filter that protects the diesel injecting device.

4.1 General

The assembly shall be manufactured in accordance with the product drawings and technical documents approved by the prescribed procedures, and its technical requirements shall comply with the provisions of this Standard.

4.2 Performance

4.2.1 Sealing property

4.2.1.1 Test according to 5.1 in QC/T 772-2017.

4.2.1.2 The assembly is installed on a test bench; inject the dry air of the specified pressure (or the pressure required by the test program) inside. The holding time is at least 1 min. The joint surface and the sealing surface of the assembly are allowed not to be leaked (no bubbles overflow).

4.2.1.3 The technical requirements for the sealing property of the assembly are given in Table 1.

Diesel filter installed before the oil transfer pump: if the internal pressure of the assembly reaches 400Pa, the joint surface, sealing surface and all positions of the assembly are not allowed to be leaked (no bubbles overflow).

Diesel filter installed after the oil transfer pump: if the internal pressure of the assembly reaches 500Pa, the joint surface, sealing surface and all positions of the assembly are not allowed to be leaked (no bubbles overflow).

4.2.2 Integrity of filter element

4.2.2.1 Test on the integrity of filter element shall be conducted as per GB/T 14041.1- 2007.

4.2.12.2

Meet the requirements of 4.2.1 for sealing property. Disassemble the diesel filter to check whether the internal filter element is de-glued, whether the joint is reliable, whether the filter paper is cracked, whether there are defects such as plastic swelling and metal corrosion.

4.2.13 Vibration fatigue

4.2.13.1 Test according to 5.9 in QC/T 772-2017.

4.2.13.2 The assembly is installed in the way of loading (machine). After the vibration fatigue test is performed under the prescribed vibration parameters, the following defects are not allowed, such as permanent deformation, cracking, leakage at the seal connection, and swelling deformation of the seal ring.

4.2.13.3 Before the assembly test, the sealing test shall be carried out in accordance with 5.1 in QC/T 772-2017; and after confirming that it meets the requirements of 4.2.1, the vibration fatigue test shall be performed. After the test, recheck whether the sealing property meet the requirements, and whether conform to the provisions of 4.2.13.2.

4.2.13.4 Before the assembly test, there is test oil inside it, and the maintained oil pressure is (34.5 ± 0.1) kPa. During and after the test, check whether there is any test oil leakage or the oil pressure is reduced, and whether conform to the provisions of 4.2.13.2.

4.2.14 Sealing ring material

4.2.14.1 The seal ring of the assembly shall be made of a diesel-resistant elastic material.

4.2.14.2 The performance of the seal ring of the assembly meets the performance requirements of HG/T 4392-2012.

4.2.15 Anti-rust treatment

4.2.15.1 All parts made of steel material in the assembly shall take the anti-rust treatment.

4.2.15.2 According to the provisions of GB/T 10125-2012, passing the neutral salt spray test for 100h is considered qualified.

4.3 Appearance

4.3.1 The visual inspection of the assembly and filter element is performed by visual examination, unless otherwise specified.

4.3.2 The outer surface of the assembly shall be smooth and flat, and no defects such as wrinkles, bumps, sharp corners, burrs, etc. are allowed.

4.3.3 The plating and coating on the surface of the assembly shall be uniform and smooth; and no defects such as dirt, sagging, exposed bottom, peeling, etc. are allowed.

5.1 Pass the inspection

Each product shall pass the inspection of the quality inspection department and be attached with a product certificate before leaving the factory.

5.2 Exit-factory inspection

5.2.1 The inspection items are 4.2.1 and 4.3.

5.2.2 When the ordering organization conducts random inspection of products, it shall be conducted in accordance with the provisions of GB/T 2828. The sampling plan and the qualified quality level AQL value shall be agreed between the supplier and the purchaser.

5.3 Type inspection

5.3.1 Selection of type inspection.

Type inspection should be carried out in one of the following cases:

a) When finalizing and identifying the new products;

b) When the major changes in structure, materials and processes may affect the performance, after the normal production;

c) When in normal production, inspection shall be carried out every 2 years;

d) When there is a big difference between the exit-factory inspection result and the latest type inspection result;

e) When a national quality supervision agency requests a type inspection.

5.3.2 The items for type inspection are all items specified in Clause 4. The vibration fatigue test of the assembly is an optional test item.

5.3.3 The sampling plan shall be agreed between the supplier and the purchaser, but shall be no less than 3 pieces.