YAMADA NDP-20, NDP-32, NDP-25 Maintenance Manual

MAINTENANCE MANUAL

YAMADA AIR-OPERATED DIAPHRAGM PUMPS

NDP-20
NDP-25
NDP-32

Doc. No. NDP 187M-10

WARNING

• For your own safety, be sure to read these procedures carefully before performing
maintenance on this product. After reading this document, be sure to keep it handy for
future reference.

This maintenance manual covers what you should know about maintenance of the Yamada NDP-20 series,
NDP-25 and NDP-32 series Diaphragm Pumps.
This edition is based on the standards for the May 2015 production run. Remember, the specifications are
always subject to change; therefore, some of the information in this edition may not apply to new
specifications.

·Warnings and Cautions

For safe use of this product, be sure to note the following: In this document, warnings and cautions are
indicated by symbols. These symbols are for those who will operate this product and for those who will be
nearby, for safe operation and for prevention of personal injury and property damage. The following
warning and caution symbols have the meanings described below. Be sure to remember their meanings.

If you ignore the warning described and operate the product in
an improper manner, there is danger of serious bodily injury or

death.

If you ignore the caution described and operate the product in an

improper manner. There is danger of personal injury or property

damage.

Furthermore, to indicate the type of danger and damage, the following symbols are also used along with
those mentioned above:

This symbol indicates a DON'T, and will be accompanied by an explanation on something
you must not do.

This symbol indicates a DO, and will be accompanied by instructions on something you
must do in a certain situation.

WARNING

• Before starting maintenance work, cut off the feed air and clean the pump. If air pressure or
residue remain in the pump, there is danger of explosion, or possible poisoning resulting in
serious injury or death if chemicals adhere to the skin or are accidentally swallowed.
(For details on cleaning the pump, refer to Chapter 6 of the Operation Manual.)

• When replacing parts, be sure to use the recommended genuine parts or Equivalents. Use of
other parts may cause a malfunction of the product.
(Refer to Exploded View and Reminder to order correct item on the separate sheets.)

CAUTION

• When it is instructed that special tools must be used, be sure to use the specified tools.
Otherwise, the pump may be damaged.

• Refer to 10.1 "Specifications" in the Operation Manual. Also, remember that the pump is
heavy, and extreme care must be taken when lifting it.

WARNING :

CAUTION :

Table of Contents

·Warnings and Cautions

·

Table of Contents

1. Principles of operation ···································································· 1

2. Tools, etc.

2.1 General tools················································································ 1

2.2 Special tools················································································· 1

2.3 Misc. ·························································································· 1

3. Ordering Replacement parts ··························································· 1

4. Balls and Valve seats

4.1 Removal

■BA□[-D], BS□, BF□ types ···························································· 2

■BP□, BV□ types·········································································· 3

4.2 Inspection ··················································································· 4

4.3 Installation·················································································· 4

5. Diaphragm and Center rod

5.1 Removal

■BA□[-D], BS□, BF□ types ···························································· 5

■BP□, BV□ types·········································································· 5

5.2 Inspection ··················································································· 6

5.3 Installation

■B□C[-D], B□N[-D], B□E, B□V, B □H[-D], B□S, B□H/T types ············ 7

■B□T[-D] types ············································································· 7

6. Throat bearing and Pilot valve Assembly

6.1 Removal ······················································································ 8

6.2 Inspection ··················································································· 8

6.3 Installation·················································································· 8

7. C Spool Valve Assembly and Sleeve Assembly

7.1 Removal ······················································································ 9

7.2 Inspection ··················································································· 9

7.3 Installation·················································································· 9

8. Retightening of Tie rods································································ 10

1

1. Principles of operation

There are two diaphragms fixed to the center rod, one at each end. When compressed air is supplied to air
chamber b (right side, see Fig.1.1), the center rod moves to the right, the material in material chamber B
is pushed out, and at the same time material is sucked into material chamber A.
When the center rod is moved full-stroke to the right, the air switch valve is switched, compressed air is
sent to air chamber a (left side, see Fig.1.2), and the center rod moves to the left. The material in
material chamber A is pushed out, and at the same time material is sucked into material chamber B.
Through repetition of this operation, material is repeatedly taken in and discharged out.

2. Tools, etc.

2.1 General tools

·Socket wrenches 10mm, 12mm, 13mm, 17mm, 22mm

·Hexagonal box wrenches 5mm

·Open-end wrenches 13mm (BP

□, BV□), 22mm (BA□[-D], BS□, BF□)

2.2 Special tools

·Accessory tool (Included) ·Sleeve remover (sold separately)
Purpose: Removing the center disk Purpose: For removing sleeves

of BP

□ and BV□ types

2.3 Misc.

·Assembly oil Turbine oil none addition class 1(equivalent to ISO VG32 grade)

·Nuts

M14×1.5

·Grease

Urea grease grade (NLGI) No. 2

·Lubricants Equivalent to LOCTITE ANTI-SEIZE 767

3. Ordering Replacement parts

For accurate and speedy shipment of parts, be sure to order the right parts for your model to distributor.
Indicate the part numbers, descriptions, and quantities.

2

4. Balls and Valve seats

4.1 Removal

■BA□[-D], BS□, BF□ types

▪ Remove the 4 retainer bolts from the out manifold, and

remove the out manifold. [Fig.4.1]

▪ Remove the O ring, valve stopper, ball and valve seat.

[Fig.4.2]

▪ Turn over the main body assembly. [Fig.4.3]
▪ Remove the 4 retainer bolts from the in manifold, and

remove the in manifold and pump bases. [Fig.4.3]
(BA□-D and NDP-32 do not have bases.)

▪ Remove the O ring, valve seat, ball and valve stopper.

[Fig.4.4]