MengziD. DG Series Multistage Pumps

Type D pumps are designed to handle clean water or liquids with similar physical and chemical properties, free of solid particles and at temperatures below 80°C. They are ideal for applications in mining, industrial settings, and urban water supply and drainage systems.

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MengziMultistage pump

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Product Description

Overview

The DG-type pump is a multi-stage, sectional boiler feedwater pump designed for delivering clean water free of solid particles (such as abrasives) or other liquids with physicochemical properties similar to water. It is ideally suited for supplying feedwater to medium- and low-pressure boilers and can also be used as a general-purpose multi-stage centrifugal clear-water pump. The temperature of the liquid being pumped ranges from -20°C to 15°C.

Structure Description

This pump type primarily consists of a casing section, a rotor section, a balancing mechanism, a bearing section, and seals.
1. Casing Section
The casing assembly primarily consists of the suction section, middle section, discharge section, guide vanes, bearing housing, and more, with all components connected by bolts. When viewed from the drive end, the pump rotates clockwise.
2. Rotor section
The rotor assembly primarily consists of a shaft, along with components mounted on the shaft such as an impeller, sleeve, and balance disc. The components on the shaft are secured in place using a keyway and a sleeve nut, while the entire rotor is supported by bearings at both ends within the pump casing. The number of rotor blades is determined based on the pump's stage configuration.
When using this type of pump, it is essential to connect the shaft seal with a water seal. The water seal can be implemented in two ways: one utilizes the discharge liquid from the primary impeller, while the other involves introducing external water. In Table 2, any item marked as requiring a "water seal connection" refers specifically to the external water seal; for all other items not explicitly noted, the discharge liquid from the primary impeller is used as the water seal connection. The tightness of the shaft seal packing should be adjusted appropriately—enough to allow a slight drip of water to escape. If the temperature of the conveyed medium exceeds 80°C, it is mandatory to use water for cooling both the stuffing box and the shaft seal cooling chamber. Both the cooling water and the externally supplied water for the water seal must be clean, fresh water at ambient temperature. The cooling water pressure should be maintained between 1.5 and 3 kg/cm², while the water seal pressure must remain 0.5 to 1 kg/cm² higher than the pressure inside the sealing chamber. Please note that the water seal and shaft seal cooling chamber’s water pipe connections vary depending on the specific pump model. For detailed information on the axial positioning of these connections, refer to the pump’s structural diagram.

3. Balancing Mechanism
The balancing mechanism consists of a balance ring, balance sleeve, balance disc, and balance pipe.
4. Bearing Section
The bearing assembly primarily consists of the bearing housing and the bearings themselves. This type of pump features two kinds of bearings: sliding bearings and circulating bearings. Importantly, the bearings do not support axial forces. During operation, the rotor must be able to move freely along the axial direction within the pump casing; therefore, radial ball bearings cannot be used. For detailed information on the specific bearings used in each pump model, refer to Table 1.
5. On the pump's sealed cooling housing, apply molybdenum disulfide grease to seal the mating surfaces of the suction section, middle section, discharge section, and guide vanes. The rotor is sealed against the stationary parts using sealing rings, guide vanes, packing materials, and more. If wear on the sealing rings or guide vane sleeves begins to affect the pump’s operation and performance, they should be replaced promptly. When operating this type of pump, ensure that the packing ring is positioned correctly.

Structure Diagram

Performance Parameter Table

Model	Rotational speed	Traffic		Head (m)	Efficiency	Shaft power	Motor power	Required NPSH
D, DG6-25×3	2950	6.3	1.75	75	45	2.86	5.5	2.0
D, DG6-25×4	2950	6.3	1.75	100	45	3.81	7.5	2.0
D, DG6-25×5	2950	6.3	1.75	125	45	4.77	7.5	2.0
D, DG6-25×6	2950	6.3	1.75	150	45	5.72	11	2.0
D, DG6-25×7	2950	6.3	1.75	175	45	6.67	11	2.0
D、DG6-25×8	2950	6.3	1.75	200	45	7.63	15	2.0
D, DG6-25×9	2950	6.3	1.75	225	45	8.52	15	2.0
D, DG6-25×10	2950	6.3	1.75	250	45	9.53	18.5	2.0
D, DG6-25×11	2950	6.3	1.75	275	45	10.5	18.5	2.0
D, DG6-25×12	2950	6.3	1.75	300	45	11.44	18.5	2.0
D, DG12-25×3	2950	12.5	3.47	75	54	4.73	7.5	2.0
D, DG12-25×4	2950	12.5	3.47	100	54	6.30	11	2.0
D, DG12-25×5	2950	12.5	3.47	125	54	7.88	11	2.0
D. DG12-25×6	2950	12.5	3.47	150	54	9.46	15	2.0
D, DG12-25×7	2950	12.5	3.47	175	54	11.0	15	2.0
D. DG12-25×8	2950	12.5	3.47	200	54	12.51	18.5	2.0
D, DG12-25×9	2950	12.5	3.47	225	54	14.18	18.5	2.0
D, DG12-25×10	2950	12.5	3.47	250	54	15.76	22	2.0
D, DG12-25×11	2950	12.5	3.47	275	54	17.34	22	2.0
D. DG12-25×12	2950	12.5	3.47	300	54	18.9	30	2.0
D、DG25-30×3	2950	25	6.94	90	62	9.88	15	2.2
D. DG25-30×4	2950	25	6.94	120	62	13.1	18.5	2.2
D. DG25-30×5	2950	25	6.94	150	62	16.47	22	2.2
D. DG25-30×6	2950	25	6.94	180	62	19.77	30	2.2
D. DG25-30×7	2950	25	6.94	210	62	23.1	30	2.2
D. DG25-30×8	2950	25	6.94	240	62	26.4	37	2.2
D、DG25-30×9	2950	25	6.94	270	62	29.65	37	2.2
D. DG25-30×10	2950	25	6.94	300	62	32.9	45	2.2
D, DG46-30×3	2950	46	12.8	90	70	16.11	22	3.0
D, DG46-30×4	2950	46	12.8	120	70	21.48	30	3.0
D, DG46-30×5	2950	46	12.8	150	70	26.85	37	3.0
D, DG46-30×6	2950	46	12.8	180	70	32.21	37	3.0
D, DG46-30×7	2950	46	12.8	210	70	37.58	45	3.0
D, DG46-30×8	2950	46	12.8	240	70	42.95	55	3.0
D, DG46-30×9	2950	46	12.8	270	70	48.32	55	3.0
D, DG46-30×10	2950	46	12.8	300	70	53.69	75	3.0
D, DG46-50×3	2950	46	12.8	150	63	29.83	37	2.8
D, DG46-50×4	2950	46	12.8	200	63	39.77	45	2.8

Model	Rotational speed	Traffic		Head (m)		Required shaft power	Motor power	Required NPSH
D, DG46-50×5	2950	46	12.8	250	63	49.71	55	2.8
D. DG46-50×6	2950	46	12.8	300	63	59.65	75	2.8
D, DG46-50×7	2950	46	12.8	350	63	69.6	90	2.8
D, DG46-50×8	2950	46	12.8	400	63	79.54	90	2.8
D, DG46-50×9	2950	46	12.8	450	63	89.48	110	2.8
D. DG46-50×10	2950	46	12.8	500	63	99.42	110	2.8
D. DG46-50×11	2950	46	12.8	550	63	109.36	132	2.8
D, DG46-50×12	2950	46	12.8	600	63	119.3	132	2.8
DG85-45×2	2950	85	23.6	90	72	28.94	37	4.2
DG85-45×3	2950	85	23.6	135	72	43.4	55	4.2
DG85-45×4	2950	85	23.6	180	72	57.87	75	4.2
DG85-45×5	2950	85	23.6	225	72	72.34	90	4.2
DG85-45×6	2950	85	23.6	270	72	86.81	110	4.2
DG85-45×7	2950	85	23.6	315	72	101.3	132	4.2
DG85-45×8	2950	85	23.6	360	72	115.7	132	4.2
DG85-45×9	2950	85	23.6	405	72	130.2	160	4.2
DG155-30×2	2950	155	43	60	77	32.84	55	3.2
DG155-30×3	2950	155	43	60	77	49.26	75	3.2
DG155-30×4	2950	155	43	120	77	65.68	90	3.2
DG155-30×5	2950	155	43	150	77	82.10	110	3.2
DG155-30×6	2950	155	43	180	77	98.52	132	3.2
DG155-30×7	2950	155	43	210	77	114.97	160	3.2
DG155-30×8	2950	155	43	240	77	131.36	180	3.2
DG155-30×9	2950	155	43	270	77	147.78	180	3.2
DG155-30×10	2950	155	43	300	77	164.20	225	3.2
D, DG155-67×3	2950	155	43	201	74	114.7	132	5.0
D, DG155-67×4	2950	155	43	268	74	152.6	185	5.0
D, DG155-67×5	2950	155	43	335	74	191.1	220	5.0
D, DG155-67×6	2950	155	43	402	74	229.3	280	5.0
D. DG155-67×7	2950	155	43	469	74	267.5	350	5.0
D. DG155-67×8	2950	155	43	536	74	305.7	350	5.0
D, DG155-67×9	2950	155	43	603	74	344	440	5.0
DG280-43×2	1480	280	77.8	86	77	85.17	110	4.0
DG280-43×3	1480	280	77.8	129	77	127.7	150	4.0
DG280-43×4	1480	280	77.8	172	77	170.3	230	4.0
DG280-43×5	1480	280	77.8	215	77	212.9	300	4.0
DG280-43×6	1480	280	77.8	258	77	255.5	300	4.0
DG280-43×7	1480	280	77.8	301	77	298.1	350	4.0
DG280-43×8	1480	280	77.8	344	77	304.7	410	4.0
DG280-43×9	1480	280	77.8	387	77	383.2	430	4.0
DG280-65×6	1480	280	77.8	390	73	407.4	500	3.0
DG280-65×7	1480	280	77.8	455	73	475.3	680	3.0
DG280-65×8	1480	280	77.8	520	73	543.2	680	3.0
DG280-65×9	1480	280	77.8	585	73	611.1	850	3.0
DG280-65×10	1480	280	77.8	650	73	579	850	3.0
DG450-60×3	1480	450	125	180	79	229.2	360	4.2
DG450-60×4	1480	450	125	240	79	372.3	500	4.2
DG450-60×5	1480	450	125	300	79	465.4	680	4.2
DG450-60×6	1480	450	125	360	79	558.2	680	4.2
DG450-60×7	1480	450	125	420	79	651.5	850	4.2
DG450-60×8	1480	450	125	480	79	744.6	850	4.2
DG450-60×9	1480	450	125	540	79	837.7	1050	4.2
DG450-60×10	1480	450	125	600	79	930.8	1050	4.2