United States Department of Agriculture

Agricultural Marketing Service

Federal Grain Inspection Service

Directive 9160.4 November 25, 2005

Distribution: FGIS, OSP, Industry Originating Office: FMD PPMAB

The U.S. Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, 

national origin, sex, religion, age, disability, political beliefs, and marital or familial status. (Not all prohibited 

bases apply to all programs.) Persons with disabilities who require alternate means for communication of program 

information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and 

TDD).

To file a complaint, write to the USDA, Office of Civil Rights, Room 326-W, 1400 Independence Avenue, SW, 

Washington, DC 20250-9410, or call (202) 720-5964 (voice and TDD). USDA is an equal employment opportunity 

employer.

GRAIN HANDLING SYSTEM TESTING

Contents

GRAIN HANDLING SYSTEM TESTING ���������������������������������������������������������������������������������1

1. PURPOSE����������������������������������������������������������������������������������������������������������������������������

2. REPLACEMENT HIGHLIGHTS��������������������������������������������������������������������������������������������

3. BACKGROUND��������������������������������������������������������������������������������������������������������������������

4. POLICY ��������������������������������������������������������������������������������������������������������������������������������

5. ACTION��������������������������������������������������������������������������������������������������������������������������������

6. INSTRUCTIONS FOR SPECIFIC TYPES OF GATES���������������������������������������������������������

6. SAFETY��������������������������������������������������������������������������������������������������������������������������������

7. COMMENTS������������������������������������������������������������������������������������������������������������������������

8. RECORD KEEPING�������������������������������������������������������������������������������������������������������������

9. QUESTIONS ������������������������������������������������������������������������������������������������������������������������

Attachment 1 ����������������������������������������������������������������������������������������������������������������������������8
FGIS Directive 9160.4 November 25, 2005

Page 2

1. PURPOSE

This directive transmits revised requirements for regular testing of grain handling 

systems used to officially weigh grain for export to assure grain flow integrity.

2. REPLACEMENT HIGHLIGHTS

This directive supersedes Program Directive 9160.4, dated 12/15/97, and the 

instructions in Chapters 1.5.b.(2)(d)2) and 1.5.b.(2)(e) of the FGIS Weighing Handbook. 

All references to biweekly or 180-day verifications of indicating elements are replaced 

with the revised intervals stated in this directive.

3. BACKGROUND

Existing instructions require official personnel to monitor grain weighing and material

handling operations on a continuous basis to assure that all exported grain is correctly

weighed, delivered, and stowed aboard the carrier. Control panels with electrical

indicators, lock out switches, or computers with visual displays are used by official

weighers to monitor grain flow. The instructions have required monitoring devices to be

verified and documented for correct operation on a regular basis.

While these procedures verify that grain flow paths are properly set, they do not account

for the possibility of gates, spouting, or conveying systems leaking into encased 

areas of the elevator or other grain flow paths. Vulnerability to grain flow problems 

has increased as the industry has increased the number and complexity of remotely 

operated material handling systems.

4. POLICY

FGIS requires official personnel to inspect and document the condition of flow control

devices and spouting, and the proper functioning of grain level and grain flow indicating

devices at critical monitoring points. Critical monitoring points are shipping bins and

points where the amount of grain in an official flow path can be increased or decreased 

by a flow diverting device or a leak. Official flow paths carry outbound grain after it has

been weighed, inbound grain before it has been weighed, or grain that cannot be 

loaded, to be weighed back before it has been weighed.

All critical monitoring points shall be inspected; during an initial facility review, after a

major renovation of the facility or its control system, or during the six-month acceptance

test of an automated weights monitoring system (Directive 9160.3). Subsequently, all

critical monitoring points shall be inspected at least once per year, or more frequently at

the discretion of the field office manager. To minimize any hampering of facility

operations, this inspection should proceed incrementally, with only a small number of

points being checked at any one time.

Partial reviews and individual gate checks shall be conducted whenever critical

monitoring points are repaired or modified. This policy is in addition to the present 

policy where official personnel give cursory inspections of this equipment on daily 

walkthroughs. This instruction applies only to export elevators.
FGIS Directive 9160.4 November 25, 2005

Page 3

5. ACTION

Perform the following procedures at critical monitoring points in the grain flow system.

a. Develop the following checklists for each elevator:

(1) A checklist of critical monitoring points to be used for leak testing, as

described in 5.b. below, and for verifying the proper operation of limit

switches and grain flow indicators, as described in 5.c. below (Attachment

1, Table 1).

(2) For each critical monitoring point, a table of all possible settings for the

gates and the corresponding states of the indicators used to monitor grain

flow, as described in 5.c. below (Attachment 1, Tables 2 and 3).

(3) A checklist of all shipping bin gate permissives, as described in 5.e. below

(Attachment 1, Table 4).

(4) A checklist of all critical bin level sensors, as described in 5.g. below

(Attachment 1, Table 5).

The tables shown in Attachment 1 are examples only and do not prescribe a

required format. Actual checklists and limit switch check tables developed for an

elevator may follow a different format, such as leaving spaces for comments in a

checklist, or including a check table for a gate’s limit switches on the same page as

a leak checklist which includes that gate. The goal is to make the checklists and

tables complete, legible, and easy to use.

b. While grain is present, physically check the opposite sides of the gates for leaks.

Where gates have no inspection openings, verify that grain is not accumulating 

where the grain would terminate. Avoid checkpoints terminating at moving 

conveyors, legs, or drags, unless they are shut down.

c. The limit switches at a flow diverting device (gate, turnhead, valve, or distributor) 

control the display elements (such as indicator lights or icons on a computer 

display) which indicate the state of the device. The table developed in 5.a.2. shall 

show the date of verification and the names or initials of personnel performing 

the test. The table shall relate every possible position of the device to the state 

its associated indicators should display when the device is in that position. For 

example, see Attachment 1, Table 2. The complexity of the table is determined 

by the type of gate(s) used in the diversion point and the number of limit switches 

involved. A two-way diverter with two limit switches such as a basket valve has 

three possible positions: two end positions in which one limit switch is actuated 

and an intermediate position in which neither limit switch is actuated. In this 

intermediate position, both possible flow paths through the gate are OPEN, so the 

display for the gate must indicate that both paths are OPEN. The display may do 

this in any of several ways, such as by turning on indicators which show the paths 

as OPEN or by turning off indicators which show the paths as CLOSED. The 

display for a turnhead placed in an intermediate position where no limit switches 

are actuated may instead show all possible flow paths as CLOSED. In no case 

shall a display show one flow path OPEN and the rest CLOSED when, in fact, 

more than one flow path is open.
FGIS Directive 9160.4 November 25, 2005

Page 4

d. Testing of limit switch operation requires two official personnel communicating

by radio: one in the elevator at the location of the device being tested and one 

observing the corresponding display element in the control room or inspection 

lab. Ask elevator personnel to move the device into each position shown on 

the table described in (c) above. Visually verify that the device is in the correct 

position, and record on the table whether the display indicates correctly. If the 

display is incorrect, record the observed state of the indicating elements. After 

the test is completed, record the pass/fail status of the diversion point on the 

checklist. Stopping an electric or hydraulic device in an intermediate position may 

be accomplished by cutting power to the electric motor or by closing the valves to 

the hydraulic cylinder. Moving a pneumatic device to an intermediate position may 

require removing air pressure from the cylinder and moving the device manually.

e. The checklist of all shipping bin gate permissives developed in 5.a.3. shall show

the date of verification and the name or initials of the personnel performing the test. 

A shipping bin gate permissive is a control that lets FGIS prevent the bottom gate 

on a shipping bin from being opened until the grain in the bin has been graded and 

the flow path is set to the correct location. The permissive may be operated by a 

key switch on a control panel or by setting the shipping bin status on a computer 

workstation. In the latter case, the status will commonly be one of the following: 

Fill, Hold, Ship, Reject, Weighback, or Transfer, with “Hold” status keeping the gate 

closed at all times. If the status does not follow this pattern, refer to the standard 

operating procedure for the elevator’s automated weighing system. The shipping 

bin may have a display element to inform FGIS personnel of the current state of 

the permissive, such as an indicator light or a status indication on the shipping bin 

icon, or it may be necessary to view the position of the key switch.

f. Testing of shipping bin gate permissives requires two official personnel 

communicating by radio: one in the elevator at the location of the bin being tested 

and one in the control room or inspection lab. Test the gate permissive by setting 

the key switch to the “hold” position or by setting the shipping bin status to “hold” 

and asking elevator personnel to attempt to open the shipping bin gate from the 

elevator control room. Testing of any electronic logic associated with a permissive 

is not covered under this directive

g. The checklist of critical bin empty sensors developed in 5.a.4. shall show the date

of verification and the name or initials of the personnel performing the test. Testing 

of empty indicators requires two official personnel communicating by radio: one 

in the elevator at the location of the bin being tested and one observing the 

corresponding display element in the control room or inspection lab. Test the bin 

empty sensor when the bin is being emptied. Physically verify that the discharge 

stops and the bin is empty very soon after the indicator changes from “not empty” 

to “empty.” Make sure that elevator personnel do not have to activate the bin 

empty sensor by hand, such as by banging on a stuck sensor.

h. Conduct the tests during normal operations or with test grain.

i. If a gate is found leaking or a limit switch is incorrectly wired, issue a 

“Repair/Modification Notice, FGIS-9601” and immediately take the gate out of 

service until repaired.
FGIS Directive 9160.4 November 25, 2005

Page 5

6. INSTRUCTIONS FOR SPECIFIC TYPES OF GATES

a. SLIDE GATES can be used to stop or throttle the flow of grain. The bottom gates

of shipping bins are of this type. A pair of slide gates at an inverted “Y” connection 

can be used to direct grain into one of two ducts. If both gates are closed, the 

grain flow is blocked. If both gates are open, grain flows into both ducts. Properly 

functioning pneumatic slide gates have only two stable positions: fully open and 

fully closed. They may, however, get stuck partway open. Such a gate can also be 

manually positioned partway open if the gate’s air supply is cut off. Electric slide 

gates may be positioned partway open by their controls.

(1) A slide gate is normally equipped with two limit switches: one actuated

when the gate is fully closed; the other actuated when the gate is fully open. 

The fully-closed limit switch must be present as it is required for official flow 

path monitoring; however, except in certain circumstances, the fully-open 

limit switch is not required by FGIS. A pair of slide gates used to divert grain 

between two flow paths normally has four limit switches, two of which are the 

required switches which indicate when each slide is fully closed.

(2) Note that the minimum number of limit switches required to adequately

monitor any diverting device of any type is equal to the number of its outlets.

(3) Since the flow of grain is stopped only when the gate is fully closed, the

display element which indicates the gate is closed must be activated only 

by the fully closed limit switch. On some shipping bins, the bottom gate is 

required to be pulled 100 percent open to purge the shipping bin before it may 

be filled. A display element which indicates that the gate is 100 percent open 

must be activated only by the fully open limit switch.

(4) Some hoppers or garners may have several bottom gates which are opened

simultaneously to allow faster emptying, but only one display element for all of 

the gates. In such a case, each gate must have its own set of limit switches. 

The display element which indicates the gates are closed must do so only 

when the fully closed limit switches on all of the gates are activated. Any 

display element which indicates the gates are 100 percent open must do so 

only when the fully open limit switches on all of the gates are activated.

b. FLAP GATES or BASKET VALVES are used to direct grain to one of two ducts.

If the gate is stuck partway between the two end positions, grain flows into both 

ducts. A flap gate or basket valve must have two limit switches: one activated 

when the gate is in end position #1; the other activated when the gate is in end 

position #2. Since grain can flow into both ducts when the gate is between the two 

end positions, the display elements must indicate that both ducts are open when 

neither limit switch is activated.
FGIS Directive 9160.4 November 25, 2005

Page 6

c. DISTRIBUTORS or TURNHEADS are used to direct grain to one of many duct

Ideally, the flow of grain is blocked when the distributor or turnhead is positioned 

between two ducts. However, some devices allow grain to flow into both ducts 

instead. A distributor or turnhead must have one limit switch for each outlet duct 

and it must be activated when the distributor or turnhead is properly aligned with 

that duct. Normally the limit switch for a particular duct is activated by contact with 

an arm which moves with the distributor. This arm must be properly aligned with 

the distributor, or the positions indicated by the limit switches will not be accurate. 

The display element which indicates a duct is selected must be activated only by 

that duct’s limit switch. All such display elements must be off when the distributor 

is between positions. Grain flowing when all of the display elements are off is an 

alarm condition

d. PROPORTIONAL SLIDE GATES may be precisely positioned partially open to

regulate the flow rate of grain so it does not overload a conveyor or leg. These 

gates are frequently used at the bottom of shipping bins. A pair of proportional 

gates in an inverted “Y” configuration may be used to divide a grain stream 

between two destinations, such as two holds of a ship. This configuration 

may be found in a gallery. The position of the gate may be indicated by a 

CABLEACTUATED POTENTIOMETER (“pot”), which has a thin steel cable 

wrapped around a spring-loaded reel. The free end of the cable is connected to 

the gate. As the gate moves, it either pulls more cable from the reel or allows the 

reel to retract. A variable resistance element inside the potentiometer measures 

the degree of rotation of the reel and converts it to a proportional voltage, which 

is used as feedback by the control system. The FGIS flow monitoring system will 

normally be concerned only that the gate is fully closed, fully open, or at some 

specific intermediate position. The gate should be equipped with limit switches 

at those specific positions so the potentiometer can be ignored. If the limit 

switches are absent, the position of the gate must be sensed by an analog input 

device, such as an analog-to-digital converter or a comparator, which receives the 

potentiometer output directly and is under FGIS control. Testing the potentiometer 

involves moving the gate to each position of interest. If the indicating device is 

a light, it should be lighted only when the gate is in the desired position. If the 

indicating device is a numeric readout, record its value when the gate reaches the 

desired position. If the value has changed since the previous test or if the readout 

does not change smoothly, note this and notify the field office and headquarters.

6. SAFETY

Exercise caution around machinery. When testing the equipment, do not place your 

body in possible pinch points. Avoid contact with belts, drags, legs, etc., even when 

they are stopped, as machinery may start suddenly without warning. Avoid contact with 

electrical wiring or leaking hydraulic lines. Flow control devices should be positioned 

by elevator personnel, who may need to follow the location’s “Lock Out/Tag Out” 

procedures during the test.
FGIS Directive 9160.4 November 25, 2005

Page 7

7. COMMENTS

Some elevators use proximity switches as limit switches. A proximity switch is

essentially a metal detector. Instead of being actuated by a mechanical arm, it is 

actuated when a large piece of metal comes sufficiently close to the switch.

(1) Determine whether gates and limit switches are already described by the

elevator’s maintenance department. Contact elevator management to see 

if they will share gate and switch information. This could save the time for 

developing new schematic diagrams or numbering systems. However, 

carefully evaluate such records for how they pertain to the official weighing 

system and for omissions

(2) When limit switches or indicators are found incorrectly wired, answer the

questions suggested in Chapter 1 of the Weighing Handbook for 

“Unauthorized Seal or Lock Breakage Procedures” before issuing Form FGIS9601. This method will most likely assure suitable measures are taken to 

correct problems.

8. RECORD KEEPING

Checklists of critical diversion points, shipping bin permissives, and bin level sensors

will require many days to fill out. During this time, they shall be maintained at the

facility along with the tables of gate positions and indicator elements for each diversion

point. If new critical monitoring points are added or existing ones are modified, the

changes shall be included on attachments to the checklists, new tables of indicator

elements and gate positions shall be made, and the new or modified equipment shall be

tested as soon as possible. At the end of each cycle, the completed checklists and their

associated tables will be filed at the field office. Facilities served by Delegated States

will file their records with the State office and forward a copy to the supervising field

office for review. Field offices must provide the Policies, Procedures, and Market 

Analysis Branch with an annual summary that notes each export weighing facility within 

their circuit and the date that the check was completed. The office which generates the 

checklists and tables is the office of record and will store them for 5 years.

Note: Whenever a leak or an indicator malfunction is discovered, it shall be 

recorded on the checklist, regardless of whether it was discovered during a 

regularly scheduled check or at some other time.

9. QUESTIONS

Direct questions to the Policies and Procedures Branch at (202) 720-0252.
FGIS Directive 9160.4 November 25, 2005

Page 8

Attachment 1

Scale 2 System Gate Leak Diagram
FGIS Directive 9160.4 November 25, 2005

Page 9

Table 1. Scale 2 System Critical Monitoring Point Checklist 1

(See 5.a.(1) and 5.b.)

Location Date Status Initials

BVP 37 Open to TH-1

BVP 37 Closed to TH-2 2/28/97 OK MB

BVP 37 Closed to TH-1

BVP 37 Open to TH-2 2/28/97 OK MB

BVP 37 Limit Switches 3/21/97 OK MB

SVE 38 Open to BC 14

SVE 39 Closed to TH-1 2/25/97 OK NB

SVE 39 Open to TH-1

SVE 38 Closed to BC 14 2/25/97 OK NB

SVE 38 & SVE 39 Limit Switches 2/25/97

2/28/97

BAD**

OK

MB

MB

SVE 40 Open TH-2

SVE 41 Closed to BC 15 5/5/97 OK MB

SVE 41 Open to BC 15

SVE 40 Closed to TH-2 5/5/97 OK MB

SVE 40 & SVE 41 Limit Switches 5/5/97 OK MB

TH-1 set to SB 1 (may be substituted by visually verifying

alignment of spouting)

SB 3 Empty

SB 5 Empty

4/8/97 OK NB

TH-1 set to SB 3

SB 1 Empty

SB 5 Empty

4/8/97 OK NB

TH-1 set to SB 5

SB 3 Empty

SB 1 Empty

4/8/97 OK NB

TH-1 Limit Switches 4/8/97 OK NB

**FGIS 9601 Issued 2/25/97, gate taken out of service. Problem corrected 2/28/97.

 

1

 Limit switch operation is checked using a separate table of gate positions such as Table 2 for each 

 diversion point.

 The results are also summarized on the checklist for ease of reference.
FGIS Directive 9160.4 November 25, 2005

Page 10

Table 1. Scale 2 System Critical Monitoring Point Checklist (Cont.)

Location Date Status Initials

TH-2 set to SB 2

SB 4 Empty

SB 6 Empty

4/16/97 OK MB

TH-2 set to SB 4

SB 2 Empty

SB 6 Empty

4/16/97 OK MB

TH-2 set to SB 6

SB 2 Empty

SB 4 Empty

4/16/97 OK MB

TH-2 Limit Switches 4/16/97 OK MB

SVE 43 (SB 1) Closed and SVE 44(or 45) Open 2/25/97 OK NB

SVE 43 Limit Switches 2/25/97 OK NB

SVE 46 (SB 3) Closed and SVE 47 (or 48) Open 5/15/97 OK MB

SVE 46 Limit Switches 5/15/97 OK MB

SVE 49 (SB 5) Closed and SVE 50 (or 51) Open 7/21/97 OK MB

SVE 49 Limit Switches 7/21/97 OK MB

SVE 52 (SB 2) Closed and SVE 53 (or 54) Open 3/6/97 OK NB

SVE 52 Limit Switches 3/6/97 OK NB

SVE 55 (SB 4) Closed and SVE 56 (or 57) Open 6/17/97 OK NB

SVE 55 Limit Switches 6/17/97 OK NB

SVE 58 (SB 6) Closed and SVE 59 (or 60) Open 4/8/97 OK MB

SVE 58 Limit Switches 4/8/97 OK MB

SVE 43 (SB 1) Open and SVE 45 Closed 5/20/97 OK NB

SVE 43 (SB 1) Open and SVE 44 Closed 5/20/97 OK NB

SVE 44 & 45 Limit Switches 4/29/97 OK MB

SVE 46 (SB 3) Open and SVE 48 Closed 4/18/97 OK MB

SVE 46 (SB 3) Open and SVE 47 Closed 4/18/97 OK MB

SVE 47 & 48 Limit Switches 4/18/97 OK MB

SVE 49 (SB 5) Open and SVE 51 Closed 3/25/97 OK NB

SVE 49 (SB 5) Open and SVE 50 Closed 3/25/97 OK NB

SVE 50 & 51 Limit Switches 3/25/97 OK NB

SVE 52 (SB 2) Open and SVE 54 Closed 5/2/97 OK NB

SVE 52 (SB 2) Open and SVE 53 Closed 5/2/97 OK NB

SVE 53 & 54 Limit Switches 5/2/97 OK NB

SVE 55 (SB 4) Open and SVE 57 Closed 5/14/97 OK MB

SVE 55 (SB 4) Open and SVE 56 Closed 5/14/97 OK MB

SVE 56 & 57 Limit Switches 5/14/97 OK MB

SVE 58 (SB 6) Open and SVE 60 Closed 6/12/97 OK NB

SVE 58 (SB 6) Open and SVE 59 Closed 6/12/97 OK NB

SVE 59 & 60 Limit Switches 6/12/97 OK NB
FGIS Directive 9160.4 November 25, 2005

Page 11

Table 2. BVP 37 Limit Switch Check Table

(See 5.a.(2))

Settings

Indicators Checked

BVP 37 to

TH-1 Open

BVP 37 to

TH-2 Open Date Status Initials

BVP 37 to TH-1 On Off 3/21/97 Okay MB

BVP 37 in

Intermediate

Position

On On 3/21/97 Okay MB

BVP 37 to TH-2 Off On 3/21/97 Okay MB

Table 3. SVE 38&39 Limit Switch Check Table

(See 5.a.(2))

Settings Indicators Checked

SVE 38 SVE 39 SVE 38

Open

SVE 39

Open

SVE 38

FO

SVE 39

FO Date Status Initials

FC FC Off Off Off Off 2/25/97 Okay MB

FC Middle Off On Off Off 2/25/97 Okay MB

FC FO Off On Off On 2/25/97 Okay MB

Middle FO X On X On Off On 2/25/97 BAD MB

Middle Middle X On X On Off Off 2/25/97 BAD MB

Middle FC X On X Off Off Off 2/25/97 BAD MB

FO FC On Off On Off 2/25/97 Okay MB

FO Middle On On On Off 2/25/97 Okay MB

FO FO On On On On 2/25/97 Okay MB
FGIS Directive 9160.4 November 25, 2005

Page 12

Table 4. Scale 2 System Shipping Bin Gate Permissive Checklist

(See 5.e.)

Location

Settings

AMS

Controls2

Setting

Elevator

Controls3

Checked

Date Initials Status

SVE 43 Hold Reclaim 2/25/97 MB Okay

SVE 46 Hold Reclaim 5/15/97 MB Okay

SVE 49 Hold Reclaim 7/21/97 MB Okay

SVE 52 Hold Reclaim 3/6/97 MB Okay

SVE 55 Hold Reclaim 6/17/97 MB Okay

SVE 58 Hold Reclaim 4/8/97 MB Okay

Table 5. Bin Empty Indicator Verification

(See 5.g.)

Shipping Bin Empty Sensors

Location 1 2 3 4 5 6

Status OK OK OK OK OK OK

Date 8/5/97 7/19/97 3/22/97 5/20/97 6/11/97 3/19/97

Initials MB MB NB NB NB MB

 

2

Put the switch (permissive) under Federal supervision in the neutral or “HOLD” postion.

3

Go into the elevator control room and have them attempt to activate the gate back to the house while the 

 permissive is set to “HOLD”, e.g., SVE 45.
FGIS Directive 9160.4 November 25, 2005

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FGIS Directive 9160.4 November 25, 2005

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FGIS Directive 9160.4 November 25, 2005

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